diff --git a/src/sys/nact.h b/src/sys/nact.h
index 8381e04..ff92bec 100644
--- a/src/sys/nact.h
+++ b/src/sys/nact.h
@@ -25,6 +25,7 @@
 #define MAX_STRVAR 10
 
 #define TRACE(fmt, ...) if (config.trace) trace(fmt "\n", ##__VA_ARGS__)
+#define TRACE_UNIMPLEMENTED(fmt, ...) trace("Unimplemented command " fmt "\n", ##__VA_ARGS__)
 
 class AGS;
 class MAKO;
diff --git a/src/sys/nact_sys1.cpp b/src/sys/nact_sys1.cpp
index f3146ba..7c12a99 100644
--- a/src/sys/nact_sys1.cpp
+++ b/src/sys/nact_sys1.cpp
@@ -485,7 +485,7 @@ void NACT_Sys1::cmd_z()
 	int cmd = cali();
 	int param = cali();
 
-	WARNING("Unimplemented command: Z %d,%d:", cmd, param);
+	TRACE_UNIMPLEMENTED("Z %d,%d:", cmd, param);
 }
 
 
@@ -944,14 +944,20 @@ public:
 
 		TRACE("Z %d,%d:", cmd, param);
 
-		if (cmd == 10) {
+		switch (cmd) {
+		case 10:
 			// nop
-		} else if (cmd == 20) {
+			break;
+		case 20:
 			if (param == 20) {
 				ags->gcopy(8, 8, 46, 144, 2);
 			} else if (param == 21) {
 				ags->gcopy(8, 8, 46, 144, 3);
 			}
+			break;
+		default:
+			WARNING("Unimplemented command: Z %d, %d", cmd, param);
+			break;
 		}
 	}
 };
diff --git a/src/sys/nact_sys2.cpp b/src/sys/nact_sys2.cpp
index 6178e56..aee1170 100644
--- a/src/sys/nact_sys2.cpp
+++ b/src/sys/nact_sys2.cpp
@@ -387,7 +387,8 @@ void NACT_Sys2::cmd_b()
 
 	TRACE("B %d,%d,%d,%d,%d,%d,%d:", cmd, index, p1, p2, p3, p4, p5);
 
-	if(cmd == 1) {
+	switch (cmd) {
+	case 1:
 		if (game_id.is(GameId::AYUMI_FD) || game_id.is(GameId::AYUMI_HINT) || game_id.is(GameId::DRSTOP)) {
 			p5 = 1;
 		}
@@ -402,7 +403,8 @@ void NACT_Sys2::cmd_b()
 			free(ags->menu_w[index - 1].screen);
 			ags->menu_w[index - 1].screen = NULL;
 		}
-	} else if(cmd == 2) {
+		break;
+	case 2:
 		if (game_id.is(GameId::AYUMI_FD) || game_id.is(GameId::AYUMI_HINT) || game_id.is(GameId::DRSTOP)) {
 			p1 = 1;
 		}
@@ -411,7 +413,8 @@ void NACT_Sys2::cmd_b()
 //		} else
 		ags->menu_w[index - 1].frame = p1 ? true : false;
 		menu_window = index;
-	} else if(cmd == 3) {
+		break;
+	case 3:
 		ags->text_w[index - 1].sx = p1 * 8;
 		ags->text_w[index - 1].sy = p2;
 		ags->text_w[index - 1].ex = p3 * 8 - 1;
@@ -428,7 +431,8 @@ void NACT_Sys2::cmd_b()
 			free(ags->text_w[index - 1].window);
 			ags->text_w[index - 1].window = NULL;
 		}
-	} else if(cmd == 4) {
+		break;
+	case 4:
 		if (game_id.is(GameId::AYUMI_FD) || game_id.is(GameId::AYUMI_HINT)) {
 			p1 = 1;
 			//p5 ? 0 : 1; // 逆？
@@ -448,6 +452,10 @@ void NACT_Sys2::cmd_b()
 			// ウィンドウ復帰
 			ags->close_text_window(index, text_window == index ? true : false);
 		}
+		break;
+	default:
+		WARNING("Unimplemented command: B %d,%d,%d,%d,%d,%d,%d:", cmd, index, p1, p2, p3, p4, p5);
+		break;
 	}
 }
 
@@ -462,7 +470,7 @@ void NACT_Sys2::cmd_d()
 	int p7 = cali();
 	int p8 = cali();
 
-	TRACE("D %d,%d,%d,%d,%d,%d,%d,%d:", p1, p2, p3, p4, p5, p6, p7, p8);
+	TRACE_UNIMPLEMENTED("D %d,%d,%d,%d,%d,%d,%d,%d:", p1, p2, p3, p4, p5, p6, p7, p8);
 }
 
 void NACT_Sys2::cmd_e()
@@ -471,7 +479,7 @@ void NACT_Sys2::cmd_e()
 	int p2 = cali();
 	int p3 = cali();
 
-	TRACE("E %d,%d,%d:", p1, p2, p3);
+	TRACE_UNIMPLEMENTED("E %d,%d,%d:", p1, p2, p3);
 }
 
 void NACT_Sys2::cmd_g()
@@ -546,7 +554,7 @@ void NACT_Sys2::cmd_i()
 //	int p3 = sco.getd();
 	int p3 = cali();
 
-	TRACE("I %d,%d,%d:", p1, p2, p3);
+	TRACE_UNIMPLEMENTED("I %d,%d,%d:", p1, p2, p3);
 }
 
 void NACT_Sys2::cmd_j()
@@ -554,7 +562,7 @@ void NACT_Sys2::cmd_j()
 	int p1 = cali();
 	int p2 = cali();
 
-	TRACE("J %d,%d:", p1, p2);
+	TRACE_UNIMPLEMENTED("J %d,%d:", p1, p2);
 }
 
 void NACT_Sys2::cmd_k()
@@ -604,7 +612,7 @@ void NACT_Sys2::cmd_n()
 	int p1 = cali();
 	int p2 = cali();
 
-	TRACE("N %d,%d:", p1, p2);
+	TRACE_UNIMPLEMENTED("N %d,%d:", p1, p2);
 }
 
 void NACT_Sys2::cmd_o()
@@ -613,7 +621,7 @@ void NACT_Sys2::cmd_o()
 	int width = cali();
 	int height = cali();
 
-	TRACE("O %d,%d,%d:", st, width, height);
+	TRACE_UNIMPLEMENTED("O %d,%d,%d:", st, width, height);
 
 #if 0
 	// white mesh
@@ -663,7 +671,7 @@ void NACT_Sys2::cmd_t()
 	int p2 = cali();
 	int p3 = cali();
 
-	TRACE("T %d,%d,%d:", p1, p2, p3);
+	TRACE_UNIMPLEMENTED("T %d,%d,%d:", p1, p2, p3);
 }
 
 void NACT_Sys2::cmd_u()
@@ -716,7 +724,7 @@ void NACT_Sys2::cmd_v()
 	int p28 = cali();
 	int p29 = cali();
 
-	TRACE("V %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d:",
+	TRACE_UNIMPLEMENTED("V %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d:",
 	cmd, p01, p02, p03, p04, p05, p06, p07, p08, p09, p10, p11, p12, p13, p14, p15, p16, p17, p18, p19, p20, p21, p22, p23, p24, p25, p26, p27, p28, p29);
 }
 
@@ -889,7 +897,7 @@ void NACT_Sys2::cmd_z()
 	int cmd = cali();
 	int param = cali();
 
-	TRACE("Z %d,%d:", cmd, param);
+	TRACE_UNIMPLEMENTED("Z %d,%d:", cmd, param);
 
 // Z1
 // Z2
diff --git a/src/sys/nact_sys3.cpp b/src/sys/nact_sys3.cpp
index 07eb97e..b9a1700 100644
--- a/src/sys/nact_sys3.cpp
+++ b/src/sys/nact_sys3.cpp
@@ -249,7 +249,8 @@ void NACT_Sys3::cmd_b()
 
 	TRACE("B %d,%d,%d,%d,%d,%d,%d:", cmd, index, p1, p2, p3, p4, p5);
 
-	if(cmd == 1) {
+	switch (cmd) {
+	case 1:
 		// あゆみちゃん物語
 		if (game_id.is(GameId::AYUMI_CD) || game_id.is(GameId::AYUMI_LIVE_256) || game_id.is(GameId::AYUMI_LIVE_FULL)) {
 			p5 = 1;
@@ -265,10 +266,12 @@ void NACT_Sys3::cmd_b()
 			free(ags->menu_w[index - 1].screen);
 			ags->menu_w[index - 1].screen = NULL;
 		}
-	} else if(cmd == 2) {
+		break;
+	case 2:
 		ags->menu_w[index - 1].frame = p1 ? true : false;
 		menu_window = index;
-	} else if(cmd == 3) {
+		break;
+	case 3:
 		ags->text_w[index - 1].sx = column ? p1 * 8 : p1 & 0xfff8;
 		ags->text_w[index - 1].sy = p2;
 		ags->text_w[index - 1].ex = column ? p3 * 8 - 1 : (p3 & 0xfff8) - 1;
@@ -285,7 +288,8 @@ void NACT_Sys3::cmd_b()
 			free(ags->text_w[index - 1].window);
 			ags->text_w[index - 1].window = NULL;
 		}
-	} else if(cmd == 4) {
+		break;
+	case 4:
 		if(p5 == 0) {
 			// ウィンドウ退避
 			if (game_id.is(GameId::PROG_CD) && p4) {
@@ -302,6 +306,10 @@ void NACT_Sys3::cmd_b()
 			// ウィンドウ復帰
 			ags->close_text_window(index, text_window == index ? true : false);
 		}
+		break;
+	default:
+		WARNING("Unimplemented command: B %d,%d,%d,%d,%d,%d,%d:", cmd, index, p1, p2, p3, p4, p5);
+		break;
 	}
 }
 
@@ -577,7 +585,7 @@ void NACT_Sys3::cmd_n()
 	int src = cali();
 	int dest = cali();
 
-	TRACE("N %d,%d,%d:", cmd, src, dest);
+	TRACE_UNIMPLEMENTED("N %d,%d,%d:", cmd, src, dest);
 }
 
 void NACT_Sys3::cmd_o()