diff --git a/Assets/gamedb/gamedb_sega_sms.txt b/Assets/gamedb/gamedb_sega_sms.txt
index 6701daef48..d185513659 100644
--- a/Assets/gamedb/gamedb_sega_sms.txt
+++ b/Assets/gamedb/gamedb_sega_sms.txt
@@ -137,7 +137,7 @@ C28AA80489A467BF54FC1403029A83D3		Champions of Europe (E)	SMS	Sports;Soccer		Eur
 1F706162F833F1DCE9513988601D314B		Championship Hockey (E)	SMS	Sports;Hockey		Europe
 2C709BA8CDC3A1B7ADC5BC838EABF6F3		Chapolim x Dracula - Um Duelo Assustador (B)	SMS			Brazil
 08511C5CF0DF0941B10EBF28050AFE51		Chase H.Q. (E)	SMS	Racing		Europe
-3CD1A4C27E330BBA7703EE22AC83B856		Chase H.Q. (J) (SMSGG)	SMS	Racing		Japan
+3CD1A4C27E330BBA7703EE22AC83B856		Chase H.Q. (J) (SMSGG)	SMS	Racing	GG_in_SMS	Japan
 F90B86478445D220D386460E55F3B74F		Cheese Cat-astrophe Starring Speedy Gonzales (E) (En,Fr,De,Es)	SMS			Europe
 747A206EAAADF48714695E8B4CCEAD7E		Choplifter (UE)	SMS		StereoByte=203	USA;Europe
 B556297E5BA2B95ED3F3A76A47402E1A		Choplifter (U) (Beta)	SMS		StereoByte=203	USA
@@ -368,7 +368,7 @@ A31CBBDED45F66633FB38B1C1BEF9B08		Opa Opa (J)	SMS			Japan
 2CA2064302F51F724E1F2593369A0696		Operation Wolf (E)	SMS	Light Gun;Arcade		Europe
 F64EA159120C018E05FB95AC8533E9EB		The Ottifants (E) (En,Fr,De,Es,It)	SMS			Europe
 558C793AAB09B46BED78431348191060		Out Run 3-D (E)	SMS	Racing;PaddleSupported	3D;FM;PaddleOptional	Europe
-2A3BDD1A6C35EEEDBF1A794ABFB57B87		Out Run Europa (U) (SMSGG)	SMS	Racing		USA
+2A3BDD1A6C35EEEDBF1A794ABFB57B87		Out Run Europa (U) (SMSGG)	SMS	Racing	GG_in_SMS	USA
 458FC29765865FDAAF3F56808C94D8A6		Out Run Europa (E)	SMS	Racing		Europe
 029EE92155247F8A282D63B8A6DD23C4		Out Run (W)	SMS	Racing;Arcade	FM;WhenFMDisablePSG;PaddleOptional	World
 946F3E6C2F0F546A8EBE55C8170ECC78		Pac-Mania (E)	SMS	Arcade		Europe
@@ -409,7 +409,7 @@ FC40576778DE28CC254B588A3A46D2A6		Putt & Putter (E) (Beta)	SMS			Europe
 58B89D62438407F242BBE713F1D945CA		Quest for the Shaven Yak Starring Ren Hoek & Stimpy (B)	SMS			Brazil
 B30E60B91960A0F2A89FC133410770DF		R.C. Grand Prix (UE)	SMS	Racing		USA;Europe
 61AA7404E23836C79E2A689322FFE190		R.C. Grand Prix (UE) (Beta)	SMS	Racing		USA;Europe
-D087B25D96F3F3E9338B0B5EC4FC2AA5		R.C. Grand Prix (UE) (SMSGG)	SMS	Racing		USA;Europe
+D087B25D96F3F3E9338B0B5EC4FC2AA5		R.C. Grand Prix (UE) (SMSGG)	SMS	Racing	GG_in_SMS	USA;Europe
 FFBA9869948E2CEF2BDA6F805CC72087		Rainbow Islands - Story of the Bubble Bobble 2 (E)	SMS			Europe
 E80AE00D8924F2BADA5949BF75995D87		Rainbow Islands - The Story of Bubble Bobble 2 (B)	SMS			Brazil
 7A080A155AD6A806DA88AA1D3576D78C		Rambo - First Blood Part II (U)	SMS			USA
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IEmulator.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IEmulator.cs
index 59ab099595..e848c03d2d 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IEmulator.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IEmulator.cs
@@ -10,7 +10,7 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 		{
 			get
 			{
-				if (IsGameGear)
+				if (IsGameGear_C)
 				{
 					return GGController;
 				}
@@ -58,10 +58,14 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 				Cpu.TraceCallback = null;
 			}
 
-			if (IsGameGear == false)
+			if (IsGameGear_C == false)
 			{
 				Cpu.NonMaskableInterrupt = controller.IsPressed("Pause");
 			}
+			else
+			{
+				Cpu.NonMaskableInterrupt = controller.IsPressed("P1 Start");
+			}
 
 			if (IsGame3D && Settings.Fix3D)
 			{
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.Input.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.Input.cs
index ffbe65cd1b..58f1a4683c 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.Input.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.Input.cs
@@ -587,14 +587,14 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 
 		byte ReadPort0()
 		{
-			if (IsGameGear == false)
+			if (IsGameGear_C == false)
 			{
 				return 0xFF;
 			}
 
 			byte value = 0xFF;
 			if ((_controller.IsPressed("Pause") && !IsGameGear) ||
-				(_controller.IsPressed("P1 Start") && IsGameGear))
+				(_controller.IsPressed("P1 Start") && IsGameGear_C))
 			{
 				value ^= 0x80;
 			}
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs
index b0bfe21403..d0e5e4e27c 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs
@@ -35,6 +35,7 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 			MemoryCallbacks = new MemoryCallbackSystem(new[] { "System Bus" });
 
 			IsGameGear = game.System == "GG";
+			IsGameGear_C = game.System == "GG";
 			IsSG1000 = game.System == "SG";
 			RomData = rom;
 
@@ -91,6 +92,17 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 				OnExecFetch = OnExecMemory
 			};
 
+
+			if (game["GG_in_SMS"])
+			{
+				// skip setting the BIOS because this is a game gear game that puts the system
+				// in SMS compatibility mode (it will fail the check sum if played on an actual SMS though.)
+				IsGameGear = false;
+				IsGameGear_C = true;
+				game.System = "GG";
+				Console.WriteLine("Using SMS Compatibility mode for Game Gear System");
+			}
+
 			Vdp = new VDP(this, Cpu, IsGameGear ? VdpMode.GameGear : VdpMode.SMS, Region);
 			(ServiceProvider as BasicServiceProvider).Register<IVideoProvider>(Vdp);
 			PSG = new SN76489();
@@ -150,7 +162,7 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 				Port3E = 0xF7; // Disable cartridge, enable BIOS rom
 				InitBiosMapper();
 			}
-			else if (game.System == "SMS")
+			else if ((game.System == "SMS") && !game["GG_in_SMS"])
 			{
 				BiosRom = comm.CoreFileProvider.GetFirmware("SMS", RegionStr, false);
 
@@ -212,6 +224,7 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 		private SN76489 PSG;
 		private YM2413 YM2413;
 		public bool IsGameGear { get; set; }
+		public bool IsGameGear_C { get; set; }
 		public bool IsSG1000 { get; set; }
 
 		private bool HasYM2413 = false;
@@ -309,6 +322,7 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 			port &= 0xFF;
 			if (port < 0x40) // General IO ports
 			{
+				
 				switch (port)
 				{
 					case 0x00: return ReadPort0();