diff --git a/CMakeLists.txt b/CMakeLists.txt
index d9b63ee..4bf6dbd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -167,9 +167,9 @@ target_sources(system3 PRIVATE
   src/sys/ags_vsp2l.cpp
   src/sys/ags_window.cpp
   src/sys/dri.cpp
+  src/sys/game_id.cpp
   src/sys/msgskip.cpp
   src/sys/nact.cpp
-  src/sys/nact_crc32.cpp
   src/sys/nact_input.cpp
   src/sys/nact_sys1.cpp
   src/sys/nact_sys2.cpp
diff --git a/src/emscripten/mako.cpp b/src/emscripten/mako.cpp
index 252f1d5..ff491a2 100644
--- a/src/emscripten/mako.cpp
+++ b/src/emscripten/mako.cpp
@@ -20,11 +20,11 @@ EM_ASYNC_JS(int, muspcm_load_data, (uint8_t *buf, uint32_t len), {
 
 } // namespace
 
-MAKO::MAKO(NACT* parent, const Config& config) :
+MAKO::MAKO(const Config& config, const GameId& game_id) :
 	use_fm(true),
 	current_music(0),
 	next_loop(0),
-	nact(parent)
+	game_id(game_id)
 {
 	g_mako = this;
 	amus.open("AMUS.DAT");
diff --git a/src/generic/mako.cpp b/src/generic/mako.cpp
index 7c99029..00e2904 100644
--- a/src/generic/mako.cpp
+++ b/src/generic/mako.cpp
@@ -32,11 +32,11 @@ void FMHook(void*, Uint8* stream, int len) {
 
 } // namespace
 
-MAKO::MAKO(NACT* parent, const Config& config) :
+MAKO::MAKO(const Config& config, const GameId& game_id) :
 	use_fm(config.use_fm),
 	current_music(0),
 	next_loop(0),
-	nact(parent)
+	game_id(game_id)
 {
 	int mix_init_flags = 0;
 
@@ -130,7 +130,7 @@ void MAKO::play_music(int page)
 		SDL_UnlockMutex(fm_mutex);
 		Mix_HookMusic(&FMHook, this);
 	} else if (midi->is_available()) {
-		if (!midi->play(nact, amus, mda, page, next_loop))
+		if (!midi->play(game_id, amus, mda, page, next_loop))
 			return;
 	}
 
diff --git a/src/sdlmain.cpp b/src/sdlmain.cpp
index 196af19..3ba7773 100644
--- a/src/sdlmain.cpp
+++ b/src/sdlmain.cpp
@@ -27,6 +27,7 @@ int main(int argc, char *argv[])
 	romfsInit();
 #endif
 	Config config(argc, argv);
+	GameId game_id(config);
 
 	SDL_Init(SDL_INIT_VIDEO);
 	SDL_SetHint(SDL_HINT_TOUCH_MOUSE_EVENTS, "0");
@@ -52,15 +53,14 @@ int main(int argc, char *argv[])
 	g_renderer = SDL_CreateRenderer(g_window, -1, 0);
 
 	// system3 初期化
-	g_nact = NACT::create(config);
+	g_nact = NACT::create(config, game_id);
 
 	if (!config.save_dir.empty()) {
 		std::string path = config.save_dir;
 		if (path[path.size() - 1] == '@') {
 			path.pop_back();
-			const char* gid = g_nact->get_game_id();
-			if (gid) {
-				path += gid;
+			if (game_id.name) {
+				path += game_id.name;
 #ifdef WIN32
 				mkdir(path.c_str());
 #else
@@ -71,17 +71,16 @@ int main(int argc, char *argv[])
 		FILEIO::set_savedir(path);
 	}
 
-	const char* title = g_nact->get_title();
-	if (title) {
+	if (game_id.title) {
 		char buf[128];
-		snprintf(buf, 128, "System3-sdl2 " SYSTEM3_VERSION ": %s", title);
+		snprintf(buf, 128, "System3-sdl2 " SYSTEM3_VERSION ": %s", game_id.title);
 #ifdef __EMSCRIPTEN__
 		EM_ASM_ARGS({ xsystem35.shell.setWindowTitle(UTF8ToString($0)); }, buf);
 #else
 		SDL_SetWindowTitle(g_window, buf);
 #endif
 	} else {
-		WARNING("Cannot determine game id. crc32_a: %08x, crc32_b: %08x", g_nact->crc32_a, g_nact->crc32_b);
+		WARNING("Cannot determine game id. crc32_a: %08x, crc32_b: %08x", game_id.crc32_a, game_id.crc32_b);
 		SDL_ShowSimpleMessageBox(
 			SDL_MESSAGEBOX_WARNING, "system3",
 			"Unable to determine game ID.\n"
@@ -105,7 +104,7 @@ int main(int argc, char *argv[])
 		exit_code = g_nact->mainloop();
 		delete g_nact;
 		if (exit_code == NACT_RESTART)
-			g_nact = NACT::create(config);
+			g_nact = NACT::create(config, game_id);
 	}
 
 	SDL_DestroyRenderer(g_renderer);
diff --git a/src/sys/ags.cpp b/src/sys/ags.cpp
index 8993be5..564972f 100644
--- a/src/sys/ags.cpp
+++ b/src/sys/ags.cpp
@@ -6,7 +6,7 @@
 
 #include "ags.h"
 #include <string.h>
-#include "crc32.h"
+#include "game_id.h"
 #include "../config.h"
 #include "../fileio.h"
 
@@ -58,10 +58,10 @@ SDL_Texture* create_scanline_texture(SDL_Renderer* renderer, int width, int heig
 
 } // namespace
 
-AGS::AGS(NACT* parent, const Config& config) : nact(parent), dirty(false)
+AGS::AGS(NACT* parent, const Config& config) : nact(parent), game_id(parent->game_id), dirty(false)
 {
 	// 画面サイズ
-	if (nact->crc32_a == CRC32_GAKUEN || nact->crc32_a == CRC32_GAKUEN_ENG) {
+	if (game_id.crc32_a == CRC32_GAKUEN || game_id.crc32_a == CRC32_GAKUEN_ENG) {
 		window_width = 582;
 		screen_width = 512;
 		window_height = screen_height = 424;
@@ -178,7 +178,7 @@ AGS::AGS(NACT* parent, const Config& config) : nact(parent), dirty(false)
 	program_palette[0x0d] = SETPALETTE16(0x0, 0xf, 0xf);
 	program_palette[0x0e] = SETPALETTE16(0xf, 0xf, 0x0);
 	program_palette[0x0f] = SETPALETTE16(0xf, 0xf, 0xf);
-	if (nact->sys_ver == 1) {
+	if (game_id.sys_ver == 1) {
 		program_palette[0x10] = SETPALETTE16(0x0, 0x0, 0x0);
 		program_palette[0x11] = SETPALETTE16(0x0, 0x0, 0xf);
 		program_palette[0x12] = SETPALETTE16(0xf, 0x0, 0x0);
@@ -228,7 +228,7 @@ AGS::AGS(NACT* parent, const Config& config) : nact(parent), dirty(false)
 	// Bコマンド
 	for(int i = 0; i < 10; i++) {
 		// ウィンドウの初期位置はシステムによって異なる
-		switch (nact->crc32_a) {
+		switch (game_id.crc32_a) {
 		case CRC32_BUNKASAI:
 			SET_TEXT(i, 24, 304, 616, 384, false);
 			SET_MENU(i, 440, 18, 620, 178, true);
@@ -312,10 +312,10 @@ AGS::AGS(NACT* parent, const Config& config) : nact(parent), dirty(false)
 //		SET_BOX(i, 0, 0, 0, 631, 399);
 		SET_BOX(i, 0, 0, 0, 639, 399);
 	}
-	if (nact->sys_ver == 2) {
-		if(nact->crc32_a == CRC32_SDPS && (nact->crc32_b == CRC32_SDPS_TONO || nact->crc32_b == CRC32_SDPS_KAIZOKU)) {
+	if (game_id.sys_ver == 2) {
+		if (game_id.crc32_a == CRC32_SDPS && (game_id.crc32_b == CRC32_SDPS_TONO || game_id.crc32_b == CRC32_SDPS_KAIZOKU)) {
 			SET_BOX(0, 0, 40, 8, 598, 271);
-		} else if(nact->crc32_a == CRC32_PROSTUDENTG_FD) {
+		} else if (game_id.crc32_a == CRC32_PROSTUDENTG_FD) {
 			SET_BOX(0, 0, 64, 13, 407, 289);
 			SET_BOX(1, 0, 24, 298, 111, 390);
 			SET_BOX(2, 0, 0, 0, 639, 307);
@@ -338,7 +338,7 @@ AGS::AGS(NACT* parent, const Config& config) : nact(parent), dirty(false)
 	text_font_maxsize = 0;
 	text_space = 2;
 	text_font_size = 16;
-	if (nact->sys_ver == 1) {
+	if (game_id.sys_ver == 1) {
 		text_font_color = 15 + 16;
 		text_frame_color = 15 + 16;
 		text_back_color = 0 + 16;
@@ -352,7 +352,7 @@ AGS::AGS(NACT* parent, const Config& config) : nact(parent), dirty(false)
 	menu_dest_x = 2;
 	menu_dest_y = 0;
 	menu_font_size = 16;
-	if (nact->sys_ver == 1) {
+	if (game_id.sys_ver == 1) {
 		menu_font_color = 15 + 16;
 		menu_frame_color = 15 + 16;
 		menu_back_color = 0 + 16;
@@ -430,7 +430,7 @@ AGS::~AGS()
 void AGS::set_cg_file(const char *file_name)
 {
 	bmp_prefix = NULL;
-	if (nact->sys_ver == 3) {
+	if (game_id.sys_ver == 3) {
 		// あゆみちゃん物語 フルカラー実写版
 		if (!strcmp(file_name, "CGA000.BMP")) {
 			bmp_prefix = "CGA";
@@ -505,7 +505,7 @@ void AGS::flush_screen(bool update)
 			uint32* src = vram[0][y];
 			uint32* dest = surface_line(hBmpDest, y);
 			for(int x = 0; x < screen_width; x++) {
-				if (nact->sys_ver == 3 && src[x] & 0x80000000) {
+				if (game_id.sys_ver == 3 && src[x] & 0x80000000) {
 					// あゆみちゃん物語 フルカラー実写版
 					dest[x] = src[x] & 0xffffff;
 				} else {
@@ -524,7 +524,7 @@ void AGS::draw_screen(int sx, int sy, int width, int height)
 		uint32* dest = surface_line(hBmpDest, y);
 		for(int x = sx; x < (sx + width) && x < 640; x++) {
 			uint32 a=src[x];
-			if (nact->sys_ver == 3 && src[x] & 0x80000000) {
+			if (game_id.sys_ver == 3 && src[x] & 0x80000000) {
 				// あゆみちゃん物語 フルカラー実写版
 				dest[x] = src[x] & 0xffffff;
 			} else {
@@ -611,9 +611,9 @@ void AGS::save_screenshot(const char* path)
 }
 
 int AGS::calculate_menu_max(int window) {
-	if (nact->crc32_a == CRC32_INTRUDER)
+	if (game_id.crc32_a == CRC32_INTRUDER)
 		return 6;
-	if (nact->crc32_a == CRC32_GAKUEN || nact->crc32_a == CRC32_GAKUEN_ENG)
+	if (game_id.crc32_a == CRC32_GAKUEN || game_id.crc32_a == CRC32_GAKUEN_ENG)
 		return (menu_w[window - 1].ey - menu_w[window - 1].sy) / (menu_font_size + 4);
 	return 11;
 }
diff --git a/src/sys/ags.h b/src/sys/ags.h
index fa893a2..b9f4756 100644
--- a/src/sys/ags.h
+++ b/src/sys/ags.h
@@ -40,6 +40,7 @@ class AGS
 {
 protected:
 	NACT* nact;
+	const GameId& game_id;
 private:
 	SDL_Texture* sdlTexture;
 	SDL_Texture* scanline_texture;
diff --git a/src/sys/ags_draw.cpp b/src/sys/ags_draw.cpp
index 81c9885..f7e3f56 100644
--- a/src/sys/ags_draw.cpp
+++ b/src/sys/ags_draw.cpp
@@ -11,7 +11,7 @@
 #include <algorithm>
 #include <string.h>
 #include "dri.h"
-#include "crc32.h"
+#include "game_id.h"
 
 void AGS::load_cg(int page, int transparent)
 {
@@ -24,9 +24,9 @@ void AGS::load_cg(int page, int transparent)
 	std::vector<uint8_t> data = acg.load(page);
 	if (data.empty())
 		return;
-	switch (nact->sys_ver) {
+	switch (game_id.sys_ver) {
 	case 1:
-		switch (nact->crc32_a) {
+		switch (game_id.crc32_a) {
 		case CRC32_BUNKASAI:
 		case CRC32_GAKUEN:
 		case CRC32_GAKUEN_ENG:
@@ -46,13 +46,13 @@ void AGS::load_cg(int page, int transparent)
 		}
 		break;
 	case 2:
-		if(nact->crc32_a == CRC32_AYUMI_PROTO) {
+		if (game_id.crc32_a == CRC32_AYUMI_PROTO) {
 			// あゆみちゃん物語 PROTO
 			load_gl3(data.data(), page, transparent);
-		} else if(nact->crc32_a == CRC32_AYUMI_FD || nact->crc32_a == CRC32_AYUMI_HINT) {
+		} else if (game_id.crc32_a == CRC32_AYUMI_FD || game_id.crc32_a == CRC32_AYUMI_HINT) {
 			// あゆみちゃん物語
 			load_vsp(data.data(), page, transparent);
-		} else if(nact->crc32_a == CRC32_SDPS) {
+		} else if (game_id.crc32_a == CRC32_SDPS) {
 			// Super D.P.S
 			load_pms(data.data(), page, transparent);
 		} else {
diff --git a/src/sys/ags_pms.cpp b/src/sys/ags_pms.cpp
index 923d9b8..99b0046 100644
--- a/src/sys/ags_pms.cpp
+++ b/src/sys/ags_pms.cpp
@@ -5,7 +5,7 @@
 */
 
 #include "ags.h"
-#include "crc32.h"
+#include "game_id.h"
 #include <string.h>
 
 void AGS::load_pms(uint8* data, int page, int transparent)
@@ -41,11 +41,11 @@ void AGS::load_pms(uint8* data, int page, int transparent)
 				tmp_palette[i * 16 + j] = SETPALETTE256(r, g, b);
 			}
 		}
-		if(nact->crc32_a == CRC32_RANCE41 ||
-		   nact->crc32_a == CRC32_RANCE41_ENG ||
-		   nact->crc32_a == CRC32_RANCE42 ||
-		   nact->crc32_a == CRC32_RANCE42_ENG ||
-		   nact->crc32_a == CRC32_HASHIRIONNA2) {
+		if (game_id.crc32_a == CRC32_RANCE41 ||
+		    game_id.crc32_a == CRC32_RANCE41_ENG ||
+		    game_id.crc32_a == CRC32_RANCE42 ||
+		    game_id.crc32_a == CRC32_RANCE42_ENG ||
+		    game_id.crc32_a == CRC32_HASHIRIONNA2) {
 			// 上下16色は取得しない
 			for(int i = 1; i < 15; i++) {
 				for(int j = 0; j < 16; j++) {
@@ -54,7 +54,7 @@ void AGS::load_pms(uint8* data, int page, int transparent)
 					}
 				}
 			}
-		} else if(nact->crc32_a == CRC32_MUGENHOUYOU && transparent != -1) {
+		} else if (game_id.crc32_a == CRC32_MUGENHOUYOU && transparent != -1) {
 			// Uコマンドでは上下32色は取得しない
 			for(int i = 2; i < 14; i++) {
 				for(int j = 0; j < 16; j++) {
@@ -75,13 +75,13 @@ void AGS::load_pms(uint8* data, int page, int transparent)
 	}
 
 	// パレット展開
-	if (nact->sys_ver == 3) {
-		if((extract_palette && extract_palette_cg[page]) || nact->crc32_a == CRC32_FUNNYBEE_CD) {
-			if(nact->crc32_a == CRC32_RANCE41 ||
-			   nact->crc32_a == CRC32_RANCE41_ENG ||
-			   nact->crc32_a == CRC32_RANCE42 ||
-			   nact->crc32_a == CRC32_RANCE42_ENG ||
-			   nact->crc32_a == CRC32_HASHIRIONNA2) {
+	if (game_id.sys_ver == 3) {
+		if ((extract_palette && extract_palette_cg[page]) || game_id.crc32_a == CRC32_FUNNYBEE_CD) {
+			if (game_id.crc32_a == CRC32_RANCE41 ||
+			    game_id.crc32_a == CRC32_RANCE41_ENG ||
+			    game_id.crc32_a == CRC32_RANCE42 ||
+			    game_id.crc32_a == CRC32_RANCE42_ENG ||
+			    game_id.crc32_a == CRC32_HASHIRIONNA2) {
 				// 上下16色は展開しない
 				for(int i = 1; i < 15; i++) {
 					for(int j = 0; j < 16; j++) {
@@ -90,7 +90,7 @@ void AGS::load_pms(uint8* data, int page, int transparent)
 						}
 					}
 				}
-			} else if(nact->crc32_a == CRC32_MUGENHOUYOU && transparent != -1) {
+			} else if (game_id.crc32_a == CRC32_MUGENHOUYOU && transparent != -1) {
 				// Uコマンドでは上下32色は展開しない
 				for(int i = 2; i < 14; i++) {
 					for(int j = 0; j < 16; j++) {
diff --git a/src/sys/ags_vsp.cpp b/src/sys/ags_vsp.cpp
index a0d3ea0..a3f4200 100644
--- a/src/sys/ags_vsp.cpp
+++ b/src/sys/ags_vsp.cpp
@@ -5,7 +5,7 @@
 */
 
 #include "ags.h"
-#include "crc32.h"
+#include "game_id.h"
 #include <string.h>
 
 void AGS::load_vsp(uint8* data, int page, int transparent)
@@ -29,7 +29,7 @@ void AGS::load_vsp(uint8* data, int page, int transparent)
 	}
 
 	// Zコマンドの処理
-	if(nact->crc32_a == CRC32_AMBIVALENZ_FD || nact->crc32_a == CRC32_AMBIVALENZ_CD) {
+	if (game_id.crc32_a == CRC32_AMBIVALENZ_FD || game_id.crc32_a == CRC32_AMBIVALENZ_CD) {
 		// Z 0,numを無視する
 	} else {
 		if(palette_bank != -1) {
@@ -49,7 +49,7 @@ void AGS::load_vsp(uint8* data, int page, int transparent)
 	}
 
 	// パレット展開
-	if(nact->crc32_a == CRC32_FUNNYBEE_FD || nact->crc32_a == CRC32_FUNNYBEE_CD || nact->crc32_a == CRC32_FUNNYBEE_PATCH) {
+	if (game_id.crc32_a == CRC32_FUNNYBEE_FD || game_id.crc32_a == CRC32_FUNNYBEE_CD || game_id.crc32_a == CRC32_FUNNYBEE_PATCH) {
 		if(extract_palette_cg[page]) {
 			for(int i = 0; i < 16; i++) {
 				screen_palette[base + i] = program_palette[base + i];
@@ -143,7 +143,7 @@ void AGS::load_vsp(uint8* data, int page, int transparent)
 
 				uint32* dest;
 				// Gakuen Senki uses exact sx values rather than 8x.
-				if (nact->crc32_a == CRC32_GAKUEN || nact->crc32_a == CRC32_GAKUEN_ENG)
+				if (game_id.crc32_a == CRC32_GAKUEN || game_id.crc32_a == CRC32_GAKUEN_ENG)
 					dest = &vram[dest_screen][y + sy][(x * 8) + sx];
 				else
 					dest = &vram[dest_screen][y + sy][(x + sx) * 8];
@@ -165,7 +165,7 @@ void AGS::load_vsp(uint8* data, int page, int transparent)
 
 	// 画面更新
 	if(dest_screen == 0 && extract_cg) {
-		if (nact->crc32_a == CRC32_GAKUEN || nact->crc32_a == CRC32_GAKUEN_ENG) {
+		if (game_id.crc32_a == CRC32_GAKUEN || game_id.crc32_a == CRC32_GAKUEN_ENG) {
 			// Gakuen Senki's images were converted to VSP for the modern port, but don't always adhere to VSP's width restrictions, which demand
 			// every image width be a factor of 8. Thankfully, the exceptions are designed to fit into specific parts of the GUI, and so have
 			// consistent widths for each output position.
diff --git a/src/sys/dri.cpp b/src/sys/dri.cpp
index 1753ecc..6923749 100644
--- a/src/sys/dri.cpp
+++ b/src/sys/dri.cpp
@@ -7,7 +7,7 @@
 #include "dri.h"
 #include <memory>
 #include <string.h>
-#include "crc32.h"
+#include "game_id.h"
 #include "../fileio.h"
 
 void Dri::open(const char* file_name)
diff --git a/src/sys/nact_crc32.cpp b/src/sys/game_id.cpp
similarity index 85%
rename from src/sys/nact_crc32.cpp
rename to src/sys/game_id.cpp
index ebe2e10..ab0d60b 100644
--- a/src/sys/nact_crc32.cpp
+++ b/src/sys/game_id.cpp
@@ -1,12 +1,5 @@
-/*
-	ALICE SOFT SYSTEM 3 for Win32
-
-	[ NACT - crc32 ]
-*/
-
-#include "nact.h"
 #include <string.h>
-#include "crc32.h"
+#include "game_id.h"
 #include "../fileio.h"
 #include "config.h"
 
@@ -92,17 +85,8 @@ const CRCTable* lookup(uint32 crc32_a, uint32 crc32_b)
 	return NULL;
 }
 
-} // namespace
-
-uint32 NACT::calc_crc32(const char* file_name, const std::string& game_id)
+uint32 calc_crc32(const char* file_name)
 {
-	if (!game_id.empty()) {
-		for (const CRCTable* t = crc_table; t->id; t++) {
-			if (t->id == game_id)
-				return file_name[0] == 'A' ? t->crc32_a : t->crc32_b;
-		}
-	}
-
 	uint32 crc = 0;
 	auto fio = FILEIO::open(file_name, FILEIO_READ_BINARY);
 
@@ -130,41 +114,33 @@ uint32 NACT::calc_crc32(const char* file_name, const std::string& game_id)
 	return crc;
 }
 
-const char* NACT::get_game_id()
-{
-	if (const CRCTable* entry = lookup(crc32_a, crc32_b))
-		return entry->id;
-	return NULL;
-}
+} // namespace
 
-const int NACT::get_sys_ver(uint32 crc32_a, uint32 crc32_b)
-{
-	if (const CRCTable* entry = lookup(crc32_a, crc32_b))
-		return entry->sys_ver;
-	return 3;
-}
-
-const char* NACT::get_title()
+GameId::GameId(const Config& config)
+	: crc32_a(0), crc32_b(0), name(NULL), sys_ver(3), title(NULL), language(JAPANESE), encoding("Shift_JIS")
 {
+	if (!config.game_id.empty()) {
+		for (const CRCTable* t = crc_table; t->id; t++) {
+			if (t->id == config.game_id) {
+				crc32_a = t->crc32_a;
+				crc32_b = t->crc32_b;
+				break;
+			}
+		}
+	} else {
+		crc32_a = calc_crc32("ADISK.DAT");
+		crc32_b = calc_crc32("BDISK.DAT");
+	}
+	const CRCTable* entry = lookup(crc32_a, crc32_b);
+	if (entry) {
+		name = entry->id;
+		sys_ver = entry->sys_ver;
+		title = entry->title;
+		language = entry->language;
+		// TODO: Determine encoding from crc32
+	}
 	if (!config.title.empty())
-		return config.title.c_str();
-	if (const CRCTable* entry = lookup(crc32_a, crc32_b))
-		return entry->title;
-	return NULL;
-}
-
-Language NACT::get_language()
-{
-	if (const CRCTable* entry = lookup(crc32_a, crc32_b))
-		return entry->language;
-	return JAPANESE;
-}
-
-const char* NACT::get_encoding_name()
-{
+		title = config.title.c_str();
 	if (!config.encoding.empty())
-		return config.encoding.c_str();
-
-	// TODO: Determine encoding from crc32
-	return "Shift_JIS";
+		encoding = config.encoding.c_str();
 }
diff --git a/src/sys/crc32.h b/src/sys/game_id.h
similarity index 91%
rename from src/sys/crc32.h
rename to src/sys/game_id.h
index 0f60c78..7baa291 100644
--- a/src/sys/crc32.h
+++ b/src/sys/game_id.h
@@ -1,11 +1,7 @@
-/*
-	ALICE SOFT SYSTEM 3 for Win32
+#ifndef _GAMEID_H_
+#define _GAMEID_H_
 
-	[ crc32 database ]
-*/
-
-#ifndef _CRC32_H_
-#define _CRC32_H_
+#include <stdint.h>
 
 // ADISK.DATの先頭256bytes
 // SYSTEM1
@@ -78,4 +74,23 @@
 #define CRC32_NINGYO		0xd491e7ab	// 人魚 -蘿子-
 #define CRC32_MUGENHOUYOU	0xbb27d1ba	// 夢幻泡影
 
-#endif
+struct Config;
+
+enum Language {
+	JAPANESE = 0,
+	ENGLISH = 1,
+};
+
+struct GameId {
+	uint32_t crc32_a;  // ADISK
+	uint32_t crc32_b;  // BDISK for D.P.S -SG- and Super D.P.S
+	const char* name;
+	int sys_ver;
+	const char* title;
+	Language language;
+	const char* encoding;
+
+	explicit GameId(const Config& config);
+};
+
+#endif  // _GAMEID_H_
diff --git a/src/sys/mako.h b/src/sys/mako.h
index cda2a3a..89f2223 100644
--- a/src/sys/mako.h
+++ b/src/sys/mako.h
@@ -13,7 +13,7 @@
 #include <limits.h>
 #include <math.h>
 #include "../common.h"
-#include "nact.h"
+#include "game_id.h"
 #include "dri.h"
 
 enum BGMDevice {
@@ -27,7 +27,7 @@ struct Config;
 class MAKO
 {
 public:
-	MAKO(NACT* parent, const Config& config);
+	MAKO(const Config& config, const GameId& game_id);
 	~MAKO();
 
 	void play_music(int page);
@@ -57,7 +57,7 @@ public:
 	int next_loop;		// Y19
 
 private:
-	NACT* nact;
+	const GameId& game_id;
 	int cd_track[100];	// Z
 
 #ifndef __EMSCRIPTEN__
diff --git a/src/sys/mako_midi.cpp b/src/sys/mako_midi.cpp
index 14b5c16..003d600 100644
--- a/src/sys/mako_midi.cpp
+++ b/src/sys/mako_midi.cpp
@@ -10,9 +10,9 @@
 #include <RtMidi.h>
 
 #include "mako_midi.h"
-#include "nact.h"
+#include "game_id.h"
 #include "dri.h"
-#include "crc32.h"
+#include "game_id.h"
 
 namespace {
 
@@ -93,7 +93,7 @@ void stop_midi()
 
 class Playback {
 public:
-	static std::unique_ptr<Playback> create(NACT* nact, Dri& amus, Dri& mda, int page, int loop, int seq);
+	static std::unique_ptr<Playback> create(const GameId& game_id, Dri& amus, Dri& mda, int page, int loop, int seq);
 	Playback(uint32_t crc32_a, int loop, int seq) : crc32_a(crc32_a), loop_(loop), seq_(seq) {}
 	bool load_mml(const std::vector<uint8_t>& data);
 	void load_mda(const std::vector<uint8_t>& data);
@@ -379,9 +379,9 @@ bool Playback::play_midi(SDL_atomic_t* current_loop, SDL_atomic_t* current_mark)
 }
 
 //static
-std::unique_ptr<Playback> Playback::create(NACT* nact, Dri& amus, Dri& mda, int page, int loop, int seq)
+std::unique_ptr<Playback> Playback::create(const GameId& game_id, Dri& amus, Dri& mda, int page, int loop, int seq)
 {
-	auto playback = std::make_unique<Playback>(nact->crc32_a, loop, seq);
+	auto playback = std::make_unique<Playback>(game_id.crc32_a, loop, seq);
 
 	std::vector<uint8_t> data = amus.load(page);
 	if (data.empty())
@@ -392,7 +392,7 @@ std::unique_ptr<Playback> Playback::create(NACT* nact, Dri& amus, Dri& mda, int
 	// Load MDA
 	data = mda.load(page);
 	if (data.empty())
-		data = Dri::load_mda(nact->crc32_a, nact->crc32_b, page);
+		data = Dri::load_mda(game_id.crc32_a, game_id.crc32_b, page);
 	playback->load_mda(data);
 
 	return playback;
@@ -660,10 +660,10 @@ bool MAKOMidi::is_available()
 	return !!midiout;
 }
 
-bool MAKOMidi::play(NACT* nact, Dri& amus, Dri& mda, int page, int loop)
+bool MAKOMidi::play(const GameId& game_id, Dri& amus, Dri& mda, int page, int loop)
 {
 	int seq = ++next_seq;
-	auto playback = Playback::create(nact, amus, mda, page, loop, seq);
+	auto playback = Playback::create(game_id, amus, mda, page, loop, seq);
 	if (!playback)
 		return false;
 	SDL_AtomicSet(&current_seq, seq);
diff --git a/src/sys/mako_midi.h b/src/sys/mako_midi.h
index 41a0712..f64ef19 100644
--- a/src/sys/mako_midi.h
+++ b/src/sys/mako_midi.h
@@ -6,7 +6,7 @@
 #include <SDL.h>
 #include "../common.h"
 
-class NACT;
+struct GameId;
 class Dri;
 
 #ifdef USE_MIDI
@@ -16,7 +16,7 @@ public:
 	explicit MAKOMidi(int device);
 	~MAKOMidi();
 	bool is_available();
-	bool play(NACT* nact, Dri& amus, Dri& mda, int page, int loop);
+	bool play(const GameId& game_id, Dri& amus, Dri& mda, int page, int loop);
 	void stop();
 	bool is_playing();
 	void get_mark(int* mark, int* loop);
@@ -41,7 +41,7 @@ class MAKOMidi {
 public:
 	explicit MAKOMidi(int device) {}
 	bool is_available() { return false; }
-	bool play(NACT* nact, Dri& amus, Dri& mda, int page, int loop) { return false; }
+	bool play(const GameId& game_id, Dri& amus, Dri& mda, int page, int loop) { return false; }
 	void stop() {}
 	bool is_playing() { return false; }
 	void get_mark(int* mark, int* loop) { *mark = *loop = 0; }
diff --git a/src/sys/nact.cpp b/src/sys/nact.cpp
index ee6fe56..2cc5c96 100644
--- a/src/sys/nact.cpp
+++ b/src/sys/nact.cpp
@@ -14,19 +14,17 @@
 #include "dri.h"
 #include "../config.h"
 #include "../fileio.h"
-#include "crc32.h"
+#include "game_id.h"
 
 extern SDL_Window* g_window;
 
 // 初期化
 
-NACT::NACT(int sys_ver, uint32 crc32_a, uint32 crc32_b, const Config& config)
-	: sys_ver(sys_ver),
-	  crc32_a(crc32_a),
-	  crc32_b(crc32_b),
-	  config(config),
-	  encoding(Encoding::create(get_encoding_name())),
-	  strings(config.get_strings(encoding.get(), get_language() == ENGLISH))
+NACT::NACT(const Config& config, const GameId& game_id)
+	: config(config),
+	  game_id(game_id),
+	  encoding(Encoding::create(game_id.encoding)),
+	  strings(config.get_strings(encoding.get(), game_id.language == ENGLISH))
 {
 	platform_initialize();
 
@@ -52,7 +50,7 @@ NACT::NACT(int sys_ver, uint32 crc32_a, uint32 crc32_b, const Config& config)
 	}
 
 	// ADISK.DAT
-	if (crc32_a == CRC32_PROG_OMAKE)
+	if (game_id.crc32_a == CRC32_PROG_OMAKE)
 		sco.open("AGAME.DAT");
 	else
 		sco.open("ADISK.DAT");
@@ -91,7 +89,7 @@ NACT::NACT(int sys_ver, uint32 crc32_a, uint32 crc32_b, const Config& config)
 
 	// 各種クラス生成
 	ags = new AGS(this, config);
-	mako = new MAKO(this, config);
+	mako = new MAKO(config, game_id);
 	msgskip = new MsgSkip(this);
 
 	SDL_Init(SDL_INIT_GAMECONTROLLER);
@@ -156,7 +154,7 @@ void NACT::execute()
 		return;
 	}
 
-	if(sys_ver == 1 && sco.page() == 0 && sco.addr() == 2) {
+	if (game_id.sys_ver == 1 && sco.page() == 0 && sco.addr() == 2) {
 		opening();
 	}
 
@@ -351,7 +349,7 @@ void NACT::message(uint8 terminator)
 
 	ags->draw_text(buf, text_wait_enb);
 
-	if(crc32_a == CRC32_DPS || crc32_a == CRC32_DPS_SG || crc32_a == CRC32_DPS_SG2 || crc32_a == CRC32_DPS_SG3) {
+	if (game_id.crc32_a == CRC32_DPS || game_id.crc32_a == CRC32_DPS_SG || game_id.crc32_a == CRC32_DPS_SG2 || game_id.crc32_a == CRC32_DPS_SG3) {
 		if(!ags->draw_menu) {
 			text_refresh = false;
 		}
@@ -533,16 +531,13 @@ void NACT::select_cursor()
 	ags->select_cursor();
 }
 
-NACT* NACT::create(const Config& config) {
-	uint32 crc32_a = NACT::calc_crc32("ADISK.DAT", config.game_id);
-	uint32 crc32_b = NACT::calc_crc32("BDISK.DAT", config.game_id);
-	int sys_ver = NACT::get_sys_ver(crc32_a, crc32_b);
-	switch (sys_ver) {
+NACT* NACT::create(const Config& config, const GameId& game_id) {
+	switch (game_id.sys_ver) {
 	case 1:
-		return new NACT_Sys1(crc32_a, crc32_b, config);
+		return new NACT_Sys1(config, game_id);
 	case 2:
-		return new NACT_Sys2(crc32_a, crc32_b, config);
+		return new NACT_Sys2(config, game_id);
 	default:
-		return new NACT_Sys3(crc32_a, crc32_b, config);
+		return new NACT_Sys3(config, game_id);
 	}
 }
diff --git a/src/sys/nact.h b/src/sys/nact.h
index a435de8..c2e2b06 100644
--- a/src/sys/nact.h
+++ b/src/sys/nact.h
@@ -14,6 +14,7 @@
 #include "../common.h"
 #include "config.h"
 #include "dri.h"
+#include "game_id.h"
 #include "scenario.h"
 
 #define RND var[ 0]
@@ -87,11 +88,6 @@ class MAKO;
 class MsgSkip;
 class Encoding;
 
-enum Language {
-	JAPANESE = 0,
-	ENGLISH = 1,
-};
-
 // special codes for NACT::exit_code
 const int NACT_HALT = -1;
 const int NACT_RESTART = -2;
@@ -99,8 +95,8 @@ const int NACT_RESTART = -2;
 class NACT
 {
 public:
-	static NACT* create(const Config& config);
-	NACT(int sys_ver, uint32 crc32_a, uint32 crc32_b, const Config& config);
+	static NACT* create(const Config& config, const GameId& game_id);
+	NACT(const Config& config, const GameId& game_id);
 	virtual ~NACT();
 
 protected:
@@ -217,8 +213,6 @@ protected:
 
 	int mouse_x = 0, mouse_y = 0;
 
-	static uint32 calc_crc32(const char* file_name, const std::string& game_id);
-
 	// Y27 ダイアログ
 	void text_dialog();
 
@@ -239,20 +233,13 @@ public:
 
 	void select_cursor();
 
-	const char* get_game_id();
-	static const int get_sys_ver(uint32 crc32_a, uint32 crc32_b);
-	const char* get_title();
-	Language get_language();
-	const char* get_encoding_name();
 	void text_wait();
 	void set_skip_menu_state(bool enabled, bool checked);
 
 	bool text_wait_enb;	// テキスト表示のウェイト有効／無効
 	bool mouse_move_enabled = true;
-	int sys_ver;
-	uint32 crc32_a;		// ADISK
-	uint32 crc32_b;		// BDISK for D.P.S -SG- and Super D.P.S
 	const Config& config;
+	const GameId& game_id;
 	std::unique_ptr<Encoding> encoding;
 	Strings strings;
 
@@ -272,7 +259,7 @@ private:
 
 class NACT_Sys1 final : public NACT {
 public:
-	NACT_Sys1(uint32 crc32_a, uint32 crc32_b, const Config& config);
+	NACT_Sys1(const Config& config, const GameId& game_id);
 protected:
 	void cmd_calc() override;
 	void cmd_branch() override;
@@ -319,7 +306,7 @@ private:
 
 class NACT_Sys2 final : public NACT {
 public:
-	NACT_Sys2(uint32 crc32_a, uint32 crc32_b, const Config& config);
+	NACT_Sys2(const Config& config, const GameId& game_id) : NACT(config, game_id) {}
 protected:
 	void cmd_calc() override;
 	void cmd_branch() override;
@@ -360,7 +347,7 @@ protected:
 
 class NACT_Sys3 final : public NACT {
 public:
-	NACT_Sys3(uint32 crc32_a, uint32 crc32_b, const Config& config);
+	NACT_Sys3(const Config& config, const GameId& game_id) : NACT(config, game_id) {}
 protected:
 	void cmd_calc() override;
 	void cmd_branch() override;
diff --git a/src/sys/nact_sys1.cpp b/src/sys/nact_sys1.cpp
index 24da926..0a91494 100644
--- a/src/sys/nact_sys1.cpp
+++ b/src/sys/nact_sys1.cpp
@@ -15,7 +15,7 @@
 #include "ags.h"
 #include "mako.h"
 #include "msgskip.h"
-#include "crc32.h"
+#include "game_id.h"
 #include "../fileio.h"
 #include "encoding.h"
 #include "texthook.h"
@@ -63,10 +63,10 @@
 	} \
 }
 
-NACT_Sys1::NACT_Sys1(uint32 crc32_a, uint32 crc32_b, const Config& config)
-	: NACT(1, crc32_a, crc32_b, config)
+NACT_Sys1::NACT_Sys1(const Config& config, const GameId& game_id)
+	: NACT(config, game_id)
 {
-	switch (crc32_a) {
+	switch (game_id.crc32_a) {
 	case CRC32_DPS:
 	case CRC32_DPS_SG:
 	//case CRC32_DPS_SG2:
@@ -88,7 +88,7 @@ NACT_Sys1::NACT_Sys1(uint32 crc32_a, uint32 crc32_b, const Config& config)
 
 void NACT_Sys1::opening()
 {
-	switch (crc32_a) {
+	switch (game_id.crc32_a) {
 	case CRC32_CRESCENT:
 		mako->play_music(2);
 		ags->load_cg(1, -1);
@@ -248,7 +248,7 @@ void NACT_Sys1::cmd_set_menu()
 		ags->menu_dest_y += 2;
 		ags->draw_menu = true;
 
-		if (crc32_a == CRC32_GAKUEN || crc32_a == CRC32_GAKUEN_ENG)
+		if (game_id.crc32_a == CRC32_GAKUEN || game_id.crc32_a == CRC32_GAKUEN_ENG)
 			menu_window = 2;
 
 		output_console("\n$%x,", menu_addr[menu_index - 1]);
@@ -264,7 +264,7 @@ void NACT_Sys1::cmd_open_menu()
 		return;
 	}
 
-	if(crc32_a == CRC32_DPS || crc32_a == CRC32_DPS_SG || crc32_a == CRC32_DPS_SG2 || crc32_a == CRC32_DPS_SG3) {
+	if (game_id.crc32_a == CRC32_DPS || game_id.crc32_a == CRC32_DPS_SG || game_id.crc32_a == CRC32_DPS_SG2 || game_id.crc32_a == CRC32_DPS_SG3) {
 		if(!text_refresh) {
 			cmd_a();
 		}
@@ -320,7 +320,7 @@ void NACT_Sys1::cmd_open_verb()
 	// 表示する動詞のチェック
 	int chk[MAX_VERB], page = 0, cnt = 0;
 	
-	if (crc32_a == CRC32_GAKUEN || crc32_a == CRC32_GAKUEN_ENG)
+	if (game_id.crc32_a == CRC32_GAKUEN || game_id.crc32_a == CRC32_GAKUEN_ENG)
 		menu_window = 1;
 	int menu_max = ags->calculate_menu_max(menu_window);
 
@@ -538,7 +538,7 @@ void NACT_Sys1::cmd_a()
 	// ウィンドウ更新
 	ags->clear_text_window(text_window, true);
 
-	if(crc32_a == CRC32_DPS || crc32_a == CRC32_DPS_SG || crc32_a == CRC32_DPS_SG2 || crc32_a == CRC32_DPS_SG3) {
+	if (game_id.crc32_a == CRC32_DPS || game_id.crc32_a == CRC32_DPS_SG || game_id.crc32_a == CRC32_DPS_SG2 || game_id.crc32_a == CRC32_DPS_SG3) {
 		text_refresh = true;
 	}
 }
@@ -574,16 +574,16 @@ void NACT_Sys1::cmd_g()
 
 	output_console("\nG %d:", page);
 
-	if (crc32_a == CRC32_INTRUDER) {
+	if (game_id.crc32_a == CRC32_INTRUDER) {
 		page = (page == 97) ? 96 : (page == 98) ? 97 : page;
-	} else if (crc32_a == CRC32_GAKUEN || crc32_a == CRC32_GAKUEN_ENG) {
+	} else if (game_id.crc32_a == CRC32_GAKUEN || game_id.crc32_a == CRC32_GAKUEN_ENG) {
 		page = (page == 3) ? 94 : page;
 	}
 
 	if (enable_graphics)
 		ags->load_cg(page, -1);
 
-	if(crc32_a == CRC32_INTRUDER) {
+	if (game_id.crc32_a == CRC32_INTRUDER) {
 		if(page == 94) {
 			WAIT(400);
 		}
@@ -876,7 +876,7 @@ void NACT_Sys1::cmd_u()
 
 	output_console("\nU %d,%d:", page, transparent);
 
-	if(crc32_a == CRC32_INTRUDER) {
+	if (game_id.crc32_a == CRC32_INTRUDER) {
 		ags->load_cg(page, 11);
 
 		if(page == 5) {
@@ -917,7 +917,7 @@ void NACT_Sys1::cmd_y()
 
 	output_console("\nY %d,%d:", cmd, param);
 
-	if(crc32_a == CRC32_INTRUDER) {
+	if (game_id.crc32_a == CRC32_INTRUDER) {
 		switch(cmd) {
 			case 0:
 				ags->clear_text_window(text_window, true);
@@ -961,7 +961,7 @@ void NACT_Sys1::cmd_y()
 				quit(NACT_HALT);
 				break;
 		}
-	} else if (crc32_a == CRC32_GAKUEN || crc32_a == CRC32_GAKUEN_ENG) {
+	} else if (game_id.crc32_a == CRC32_GAKUEN || game_id.crc32_a == CRC32_GAKUEN_ENG) {
 		switch (cmd) {
 			case 1:
 				RND = (param == 0 || param == 1) ? 0 : random(param);
@@ -1025,11 +1025,11 @@ void NACT_Sys1::cmd_y()
 				}
 				break;
 			case 2:
-				if(crc32_a == CRC32_CRESCENT) {
+				if (game_id.crc32_a == CRC32_CRESCENT) {
 					for(int i = 39; i <= 48; i++) {
 						var[i] = 0;
 					}
-				} else if(crc32_a == CRC32_DPS || crc32_a == CRC32_DPS_SG || crc32_a == CRC32_DPS_SG2 || crc32_a == CRC32_DPS_SG3) {
+				} else if (game_id.crc32_a == CRC32_DPS || game_id.crc32_a == CRC32_DPS_SG || game_id.crc32_a == CRC32_DPS_SG2 || game_id.crc32_a == CRC32_DPS_SG3) {
 					for(int i = 0; i <= 20; i++) {
 						var[i] = 0;
 					}
@@ -1046,14 +1046,14 @@ void NACT_Sys1::cmd_y()
 				RND = (param == 0 || param == 1) ? 0 : random(param);
 				break;
 			case 7:
-				if(crc32_a == CRC32_DPS || crc32_a == CRC32_DPS_SG || crc32_a == CRC32_DPS_SG2 || crc32_a == CRC32_DPS_SG3) {
+				if (game_id.crc32_a == CRC32_DPS || game_id.crc32_a == CRC32_DPS_SG || game_id.crc32_a == CRC32_DPS_SG2 || game_id.crc32_a == CRC32_DPS_SG3) {
 					if(param == 1) {
 						ags->box_fill(0, 40, 8, 598, 270, 0);
 					}
 				}
 				break;
 			case 130:
-				if(crc32_a == CRC32_TENGU) {
+				if (game_id.crc32_a == CRC32_TENGU) {
 					WAIT(2000)
 					ags->load_cg(180, -1);
 
@@ -1090,7 +1090,7 @@ void NACT_Sys1::cmd_y()
 				RND = 0;
 				break;
 			case 255:
-				if(crc32_a == CRC32_DPS || crc32_a == CRC32_DPS_SG || crc32_a == CRC32_DPS_SG2 || crc32_a == CRC32_DPS_SG3) {
+				if (game_id.crc32_a == CRC32_DPS || game_id.crc32_a == CRC32_DPS_SG || game_id.crc32_a == CRC32_DPS_SG2 || game_id.crc32_a == CRC32_DPS_SG3) {
 					quit(0);
 				} else {
 					quit(NACT_HALT);
@@ -1102,7 +1102,7 @@ void NACT_Sys1::cmd_y()
 
 void NACT_Sys1::cmd_z()
 {
-	if (crc32_a == CRC32_CRESCENT) {
+	if (game_id.crc32_a == CRC32_CRESCENT) {
 		cmd_y();
 		return;
 	}
@@ -1111,7 +1111,7 @@ void NACT_Sys1::cmd_z()
 
 	output_console("\nZ %d,%d:", cmd, param);
 
-	switch (crc32_a) {
+	switch (game_id.crc32_a) {
 	case CRC32_INTRUDER:
 		if(cmd == 1 && 1 <= param && param <= 4) {
 			const char* buf[4] = {
diff --git a/src/sys/nact_sys2.cpp b/src/sys/nact_sys2.cpp
index e32fba7..c1cfb4a 100644
--- a/src/sys/nact_sys2.cpp
+++ b/src/sys/nact_sys2.cpp
@@ -10,7 +10,7 @@
 #include "ags.h"
 #include "mako.h"
 #include "msgskip.h"
-#include "crc32.h"
+#include "game_id.h"
 #include "../fileio.h"
 #include "encoding.h"
 #include "texthook.h"
@@ -58,11 +58,6 @@
 	} \
 }
 
-NACT_Sys2::NACT_Sys2(uint32 crc32_a, uint32 crc32_b, const Config& config)
-	: NACT(2, crc32_a, crc32_b, config)
-{
-}
-
 void NACT_Sys2::cmd_calc()
 {
 	int index = sco.getd();
@@ -199,7 +194,7 @@ void NACT_Sys2::cmd_branch()
 				cali();
 				cali();
 			} else if(cmd == 'U') {
-				if(crc32_a == CRC32_YAKATA2) {
+				if (game_id.crc32_a == CRC32_YAKATA2) {
 					cali();
 					cali();
 				} else {
@@ -494,7 +489,7 @@ void NACT_Sys2::cmd_b()
 	output_console("\nB %d,%d,%d,%d,%d,%d,%d:", cmd, index, p1, p2, p3, p4, p5);
 
 	if(cmd == 1) {
-		if(crc32_a == CRC32_AYUMI_FD || crc32_a == CRC32_AYUMI_HINT || crc32_a == CRC32_DRSTOP) {
+		if (game_id.crc32_a == CRC32_AYUMI_FD || game_id.crc32_a == CRC32_AYUMI_HINT || game_id.crc32_a == CRC32_DRSTOP) {
 			p5 = 1;
 		}
 		ags->menu_w[index - 1].sx = p1 * 8;
@@ -509,10 +504,10 @@ void NACT_Sys2::cmd_b()
 			ags->menu_w[index - 1].screen = NULL;
 		}
 	} else if(cmd == 2) {
-		if(crc32_a == CRC32_AYUMI_FD || crc32_a == CRC32_AYUMI_HINT || crc32_a == CRC32_DRSTOP) {
+		if (game_id.crc32_a == CRC32_AYUMI_FD || game_id.crc32_a == CRC32_AYUMI_HINT || game_id.crc32_a == CRC32_DRSTOP) {
 			p1 = 1;
 		}
-//		if(crc32_a == CRC32_PROSTUDENTG_FD) {
+//		if (game_id.crc32_a == CRC32_PROSTUDENTG_FD) {
 //			ags->menu_w[index - 1].frame = (index == 1 || index == 3) ? true : false;
 //		} else
 		ags->menu_w[index - 1].frame = p1 ? true : false;
@@ -535,16 +530,16 @@ void NACT_Sys2::cmd_b()
 			ags->text_w[index - 1].window = NULL;
 		}
 	} else if(cmd == 4) {
-		if(crc32_a == CRC32_AYUMI_FD || crc32_a == CRC32_AYUMI_HINT) {
+		if (game_id.crc32_a == CRC32_AYUMI_FD || game_id.crc32_a == CRC32_AYUMI_HINT) {
 			p1 = 1;
 			//p5 ? 0 : 1; // 逆？
 			p5 = 0;
-		} else if(crc32_a == CRC32_DRSTOP) {
+		} else if (game_id.crc32_a == CRC32_DRSTOP) {
 			p1 = 1;
 		}
 		if(p5 == 0) {
 			// ウィンドウ退避
-//			if(crc32_a == CRC32_PROSTUDENTG_FD) {
+//			if (game_id.crc32_a == CRC32_PROSTUDENTG_FD) {
 //				ags->text_w[index - 1].frame = (index == 1 || index == 3) ? true : false;
 //			} else
 			ags->text_w[index - 1].frame = p1 ? true : false;
@@ -593,18 +588,18 @@ void NACT_Sys2::cmd_g()
 
 	output_console("\nG %d:", page);
 
-	if(crc32_a == CRC32_SDPS && (crc32_b == CRC32_SDPS_TONO || crc32_b == CRC32_SDPS_KAIZOKU)) {
+	if (game_id.crc32_a == CRC32_SDPS && (game_id.crc32_b == CRC32_SDPS_TONO || game_id.crc32_b == CRC32_SDPS_KAIZOKU)) {
 		if(20 <= page && page <= 100) {
 			page--;
 		}
 	}
 	ags->load_cg(page, -1);
 
-	if(crc32_a == CRC32_DALK_HINT) {
+	if (game_id.crc32_a == CRC32_DALK_HINT) {
 		if(page == 3) {
 			WAIT(2000)
 		}
-	} else if(crc32_a == CRC32_RANCE3_HINT) {
+	} else if (game_id.crc32_a == CRC32_RANCE3_HINT) {
 		if(page == 25) {
 			WAIT(2000)
 		}
@@ -825,7 +820,7 @@ void NACT_Sys2::cmd_p()
 {
 	int param = sco.getd();
 
-	if(crc32_a != CRC32_YAKATA2 && crc32_a != CRC32_DALK_HINT && crc32_a != CRC32_RANCE3_HINT) {
+	if (game_id.crc32_a != CRC32_YAKATA2 && game_id.crc32_a != CRC32_DALK_HINT && game_id.crc32_a != CRC32_RANCE3_HINT) {
 		ags->text_font_color = (uint8)((param & 0x7) + 16);
 	}
 
@@ -966,7 +961,7 @@ void NACT_Sys2::cmd_u()
 {
 	int page, transparent;
 
-	if(crc32_a == CRC32_YAKATA2) {
+	if (game_id.crc32_a == CRC32_YAKATA2) {
 		page = cali();
 		transparent = cali();
 	} else {
@@ -1087,7 +1082,7 @@ void NACT_Sys2::cmd_y()
 			RND = (param == 0 || param == 1) ? 0 : random(param);
 			break;
 		case 7:
-			if(!(crc32_a == CRC32_SDPS && crc32_b == CRC32_SDPS_MARIA)) {
+			if (!(game_id.crc32_a == CRC32_SDPS && game_id.crc32_b == CRC32_SDPS_MARIA)) {
 				ags->draw_box(param);
 			}
 			break;
diff --git a/src/sys/nact_sys3.cpp b/src/sys/nact_sys3.cpp
index d2e89a0..0269532 100644
--- a/src/sys/nact_sys3.cpp
+++ b/src/sys/nact_sys3.cpp
@@ -10,16 +10,11 @@
 #include "ags.h"
 #include "mako.h"
 #include "msgskip.h"
-#include "crc32.h"
+#include "game_id.h"
 #include "../fileio.h"
 #include "encoding.h"
 #include "texthook.h"
 
-NACT_Sys3::NACT_Sys3(uint32 crc32_a, uint32 crc32_b, const Config& config)
-	: NACT(3, crc32_a, crc32_b, config)
-{
-}
-
 void NACT_Sys3::cmd_calc()
 {
 	int index = sco.getd();
@@ -272,7 +267,7 @@ void NACT_Sys3::cmd_b()
 
 	if(cmd == 1) {
 		// あゆみちゃん物語
-		if(crc32_a == CRC32_AYUMI_CD || crc32_a == CRC32_AYUMI_JISSHA_256 || crc32_a == CRC32_AYUMI_JISSHA_FULL) {
+		if (game_id.crc32_a == CRC32_AYUMI_CD || game_id.crc32_a == CRC32_AYUMI_JISSHA_256 || game_id.crc32_a == CRC32_AYUMI_JISSHA_FULL) {
 			p5 = 1;
 		}
 		ags->menu_w[index - 1].sx = column ? p1 * 8 : p1 & 0xfff8;
@@ -309,7 +304,7 @@ void NACT_Sys3::cmd_b()
 	} else if(cmd == 4) {
 		if(p5 == 0) {
 			// ウィンドウ退避
-			if(crc32_a == CRC32_PROSTUDENTG_CD && p4) {
+			if (game_id.crc32_a == CRC32_PROSTUDENTG_CD && p4) {
 				// prostudent G オープニング画面化け対策
 				if(ags->text_w[index - 1].window) {
 					free(ags->text_w[index - 1].window);
@@ -426,7 +421,7 @@ void NACT_Sys3::cmd_i()
 
 	// X方向はカラム単位で切り捨て
 	sx = column ? sx * 8 : sx & 0xfff8;
-	ex = column ? ex * 8 - 1 : (crc32_a == CRC32_NINGYO) ? (ex & 0xfff8) + 7 : (ex & 0xfff8) - 1;
+	ex = column ? ex * 8 - 1 : (game_id.crc32_a == CRC32_NINGYO) ? (ex & 0xfff8) + 7 : (ex & 0xfff8) - 1;
 	dx = column ? dx * 8 : dx & 0xfff8;
 	ags->copy(sx, sy, ex, ey, dx, dy);
 }
@@ -457,7 +452,7 @@ void NACT_Sys3::cmd_k()
 	}
 
 	if (cmd == 3) {
-		switch (crc32_a) {
+		switch (game_id.crc32_a) {
 		case CRC32_YAKATA3_CD:
 			if (k3_hack(yakata3cd_k3_hack_table))
 				return;
@@ -923,8 +918,8 @@ void NACT_Sys3::cmd_u()
 
 	output_console("\nU %d,%d:", page, transparent);
 
-	if(crc32_a == CRC32_RANCE41 || crc32_a == CRC32_RANCE41_ENG ||
-	   crc32_a == CRC32_RANCE42 || crc32_a == CRC32_RANCE42_ENG) {
+	if (game_id.crc32_a == CRC32_RANCE41 || game_id.crc32_a == CRC32_RANCE41_ENG ||
+	    game_id.crc32_a == CRC32_RANCE42 || game_id.crc32_a == CRC32_RANCE42_ENG) {
 		transparent = (transparent == 28) ? 12 : transparent;
 	}
 	ags->load_cg(page, transparent);
@@ -1236,7 +1231,7 @@ void NACT_Sys3::cmd_y()
 		case 231:
 			D01 = 640;
 			D02 = (param == 1) ? ags->screen_height : 480;
-			D03 = (crc32_a == CRC32_YAKATA3_FD) ? 16 : 256;
+			D03 = (game_id.crc32_a == CRC32_YAKATA3_FD) ? 16 : 256;
 			break;
 		case 232:
 			if(ags->screen_height != (param ? 480 : 400)) {
@@ -1323,13 +1318,13 @@ void NACT_Sys3::cmd_y()
 			column = param ? false : true;
 			break;
 		case 252:
-			RND = (crc32_a == CRC32_YAKATA3_FD) ? 4 : 8;
+			RND = (game_id.crc32_a == CRC32_YAKATA3_FD) ? 4 : 8;
 			break;
 		case 253:
 			show_push = (param == 0) ? true : false;
 			break;
 		case 254:
-			RND = (crc32_a == CRC32_YAKATA3_CD || crc32_a == CRC32_YAKATA3_FD || crc32_a == CRC32_NINGYO) ? 1 : 0;
+			RND = (game_id.crc32_a == CRC32_YAKATA3_CD || game_id.crc32_a == CRC32_YAKATA3_FD || game_id.crc32_a == CRC32_NINGYO) ? 1 : 0;
 			break;
 		case 255:
 			quit(param == 1 ? NACT_HALT : RND);
diff --git a/src/win/mako.cpp b/src/win/mako.cpp
index 8015789..39f3e1a 100644
--- a/src/win/mako.cpp
+++ b/src/win/mako.cpp
@@ -17,7 +17,7 @@
 #include "fm/mako_ymfm.h"
 #include "../config.h"
 #include "dri.h"
-#include "crc32.h"
+#include "game_id.h"
 
 extern SDL_Window* g_window;
 
@@ -50,7 +50,7 @@ const char* mci_geterror(DWORD err)
 
 class MCIThread {
 public:
-	MCIThread(NACT* nact, HWND hwnd_notify) : hwnd_notify(hwnd_notify) {
+	MCIThread(HWND hwnd_notify) : hwnd_notify(hwnd_notify) {
 		if (!_beginthreadex(NULL, 0, &MCIThread::run, this, 0, &thread_id))
 			sys_error("Cannot create thread: %s", strerror(errno));
 	}
@@ -200,11 +200,11 @@ void audio_callback(void*, Uint8* stream, int len) {
 
 } // namespace
 
-MAKO::MAKO(NACT* parent, const Config& config) :
+MAKO::MAKO(const Config& config, const GameId& game_id) :
 	use_fm(config.use_fm),
 	current_music(0),
 	next_loop(0),
-	nact(parent)
+	game_id(game_id)
 {
 	if (!config.playlist.empty())
 		load_playlist(config.playlist.c_str());
@@ -236,7 +236,7 @@ MAKO::MAKO(NACT* parent, const Config& config) :
 	SDL_VERSION(&info.version);
 	if (!SDL_GetWindowWMInfo(g_window, &info))
 		sys_error("SDL_GetWindowWMInfo failed: %s", SDL_GetError());
-	mci_thread = new MCIThread(parent, info.info.win.window);
+	mci_thread = new MCIThread(info.info.win.window);
 
 	midi = std::make_unique<MAKOMidi>(config.midi_device);
 	if (!midi->is_available())
@@ -299,7 +299,7 @@ void MAKO::play_music(int page)
 		SDL_UnlockMutex(fm_mutex);
 		SDL_PauseAudio(0);
 	} else if (midi->is_available()) {
-		if (!midi->play(nact, amus, mda, page, next_loop))
+		if (!midi->play(game_id, amus, mda, page, next_loop))
 			return;
 	}
 	current_music = page;
@@ -360,7 +360,7 @@ void MAKO::select_sound(BGMDevice dev)
 	case BGM_CD:
 		const int8* tracks;
 
-		switch (nact->crc32_a) {
+		switch (game_id.crc32_a) {
 		case CRC32_RANCE41:
 		case CRC32_RANCE41_ENG:
 			tracks = RANCE41_tracks;
diff --git a/src/win/nact_win.cpp b/src/win/nact_win.cpp
index e623ce0..d11369f 100644
--- a/src/win/nact_win.cpp
+++ b/src/win/nact_win.cpp
@@ -138,7 +138,7 @@ void NACT::text_dialog()
 void NACT::platform_initialize()
 {
 	init_menu(mouse_move_enabled, config);
-	init_console(sys_ver);
+	init_console(game_id.sys_ver);
 	SDL_EventState(SDL_SYSWMEVENT, SDL_ENABLE);
 }