diff --git a/include/mgba/internal/gba/cart/unlicensed.h b/include/mgba/internal/gba/cart/unlicensed.h
new file mode 100644
index 000000000..ec13abb55
--- /dev/null
+++ b/include/mgba/internal/gba/cart/unlicensed.h
@@ -0,0 +1,75 @@
+/* Copyright (c) 2013-2024 Jeffrey Pfau
+ * Copyright (c) 2016 taizou
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef GBA_UNLICENSED_H
+#define GBA_UNLICENSED_H
+
+#include <mgba-util/common.h>
+
+CXX_GUARD_START
+
+#include <mgba/core/timing.h>
+
+enum GBAVFameCartType {
+	VFAME_STANDARD = 0,
+	VFAME_GEORGE = 1,
+	VFAME_ALTERNATE = 2,
+};
+
+enum GBAUnlCartType {
+	GBA_UNL_CART_NONE = 0,
+	GBA_UNL_CART_VFAME = 1,
+	GBA_UNL_CART_MULTICART = 2,
+};
+
+struct GBAVFameCart {
+	enum GBAVFameCartType cartType;
+	int sramMode;
+	int romMode;
+	int8_t writeSequence[5];
+	bool acceptingModeChange;
+};
+
+struct GBAMulticart {
+	struct mTimingEvent settle;
+	uint32_t* rom;
+	size_t fullSize;
+
+	uint8_t bank;
+	uint8_t offset;
+	uint8_t size;
+	bool sramActive;
+	uint8_t unk;
+};
+
+struct GBAUnlCart {
+	enum GBAUnlCartType type;
+	union {
+		struct GBAVFameCart vfame;
+		struct GBAMulticart multi;
+	};
+};
+
+struct GBA;
+struct GBAMemory;
+void GBAUnlCartInit(struct GBA*);
+void GBAUnlCartReset(struct GBA*);
+void GBAUnlCartUnload(struct GBA*);
+void GBAUnlCartDetect(struct GBA*);
+void GBAUnlCartWriteSRAM(struct GBA*, uint32_t address, uint8_t value);
+
+struct GBASerializedState;
+void GBAUnlCartSerialize(const struct GBA* gba, struct GBASerializedState* state);
+void GBAUnlCartDeserialize(struct GBA* gba, const struct GBASerializedState* state);
+
+bool GBAVFameDetect(struct GBAVFameCart* cart, uint32_t* rom, size_t romSize, uint32_t crc32);
+void GBAVFameSramWrite(struct GBAVFameCart* cart, uint32_t address, uint8_t value, uint8_t* sramData);
+uint32_t GBAVFameModifyRomAddress(struct GBAVFameCart* cart, uint32_t address, size_t romSize);
+uint32_t GBAVFameGetPatternValue(uint32_t address, int bits);
+
+CXX_GUARD_END
+
+#endif
diff --git a/include/mgba/internal/gba/cart/vfame.h b/include/mgba/internal/gba/cart/vfame.h
deleted file mode 100644
index 5bee28848..000000000
--- a/include/mgba/internal/gba/cart/vfame.h
+++ /dev/null
@@ -1,41 +0,0 @@
-/* Copyright (c) 2016 taizou
- *
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-// Support for copy protected unlicensed games from the company Vast Fame
-
-#ifndef GBA_VFAME_H
-#define GBA_VFAME_H
-
-#include <mgba-util/common.h>
-
-CXX_GUARD_START
-
-#define DIGIMON_SAPPHIRE_CHINESE_CRC32 0x793A328F
-
-enum GBAVFameCartType {
-	VFAME_NO = 0,
-	VFAME_STANDARD = 1,
-	VFAME_GEORGE = 2,
-	VFAME_ALTERNATE = 3,
-};
-
-struct GBAVFameCart {
-	enum GBAVFameCartType cartType;
-	int sramMode;
-	int romMode;
-	int8_t writeSequence[5];
-	bool acceptingModeChange;
-};
-
-void GBAVFameInit(struct GBAVFameCart* cart);
-void GBAVFameDetect(struct GBAVFameCart* cart, uint32_t* rom, size_t romSize, uint32_t crc32);
-void GBAVFameSramWrite(struct GBAVFameCart* cart, uint32_t address, uint8_t value, uint8_t* sramData);
-uint32_t GBAVFameModifyRomAddress(struct GBAVFameCart* cart, uint32_t address, size_t romSize);
-uint32_t GBAVFameGetPatternValue(uint32_t address, int bits);
-
-CXX_GUARD_END
-
-#endif
diff --git a/include/mgba/internal/gba/memory.h b/include/mgba/internal/gba/memory.h
index c88e1d092..1b32763fc 100644
--- a/include/mgba/internal/gba/memory.h
+++ b/include/mgba/internal/gba/memory.h
@@ -18,7 +18,7 @@ CXX_GUARD_START
 #include <mgba/internal/gba/cart/ereader.h>
 #include <mgba/internal/gba/cart/gpio.h>
 #include <mgba/internal/gba/cart/matrix.h>
-#include <mgba/internal/gba/cart/vfame.h>
+#include <mgba/internal/gba/cart/unlicensed.h>
 
 enum GBAMemoryRegion {
 	GBA_REGION_BIOS = 0x0,
@@ -108,8 +108,8 @@ struct GBAMemory {
 
 	struct GBACartridgeHardware hw;
 	struct GBASavedata savedata;
-	struct GBAVFameCart vfame;
 	struct GBAMatrix matrix;
+	struct GBAUnlCart unl;
 	struct GBACartEReader ereader;
 	size_t romSize;
 	uint32_t romMask;
diff --git a/include/mgba/internal/gba/serialize.h b/include/mgba/internal/gba/serialize.h
index 8b1823a17..48393ed7b 100644
--- a/include/mgba/internal/gba/serialize.h
+++ b/include/mgba/internal/gba/serialize.h
@@ -186,11 +186,14 @@ mLOG_DECLARE_CATEGORY(GBA_STATE);
  *   | bit 3: Reserved
  *   | bits 4 - 15: Light counter
  * | 0x002C0 - 0x002C0: Light sample
- * | 0x002C1 - 0x002C3: Flags
+ * | 0x002C1: Flags
  *   | bits 0 - 1: Tilt state machine
  *   | bits 2 - 3: GB Player inputs posted
- *   | bits 4 - 8: GB Player transmit position
- *   | bits 9 - 23: Reserved
+ *   | bits 4 - 7: GB Player transmit position
+ * | 0x002C2 - 0x002C3: Unlicensed cart flags
+ *   | bits 0 - 4: Cartridge type
+ *   | bits 5 - 7: Cartridge subtype
+ *   | bits 8 - 15: Reserved
  * 0x002C4 - 0x002C7: SIO next event
  * 0x002C8 - 0x002CB: Current DMA transfer word
  * 0x002CC - 0x002CF: Last DMA transfer PC
@@ -230,8 +233,23 @@ mLOG_DECLARE_CATEGORY(GBA_STATE);
  * | bits 15 - 31: Reserved
  * 0x00320 - 0x00323: Next IRQ event
  * 0x00324 - 0x00327: Interruptable BIOS stall cycles
- * 0x00328 - 0x00367: Matrix memory mapping table
- * 0x00368 - 0x0036F: Reserved (leave zero)
+ * 0x00328 - 0x0036F: Special cartridge state, one of:
+ * | Matrix Memory:
+ * | 0x00328 - 0x00367: Matrix memory mapping table
+ * | 0x00368 - 0x0036F: Reserved (leave zero)
+ * | Unlicensed multicart:
+ * | 0x00328: Bank value
+ * | 0x00329: Offset value
+ * | 0x0032A: Size value
+ * | 0x0032B: SRAM active value
+ * | 0x0032C: Unknown value
+ * | 0x0032D: Current size
+ * | 0x0032E - 0x0032F: Current bank/offset
+ * | 0x00330 - 0x00333: Next settle event
+ * | 0x00334 - 0x00337: Flags
+ *   | bit 0: Is settling occuring?
+ *   | bits 1 - 31: Reserved
+ * | 0x00338 - 0x0036F: Reserved (leave zero)
  * 0x00370 - 0x0037F: Audio FIFO A samples
  * 0x00380 - 0x0038F: Audio FIFO B samples
  * 0x00390 - 0x003CF: Audio rendered samples
@@ -269,9 +287,14 @@ DECL_BITS(GBASerializedHWFlags1, LightCounter, 4, 12);
 DECL_BITFIELD(GBASerializedHWFlags2, uint8_t);
 DECL_BITS(GBASerializedHWFlags2, TiltState, 0, 2);
 DECL_BITS(GBASerializedHWFlags2, GbpInputsPosted, 2, 2);
-DECL_BITS(GBASerializedHWFlags2, GbpTxPosition, 4, 5);
+DECL_BITS(GBASerializedHWFlags2, GbpTxPosition, 4, 4);
 
-DECL_BITFIELD(GBASerializedHWFlags3, uint16_t);
+DECL_BITFIELD(GBASerializedUnlCartFlags, uint16_t);
+DECL_BITS(GBASerializedUnlCartFlags, Type, 0, 5);
+DECL_BITS(GBASerializedUnlCartFlags, Subtype, 5, 3);
+
+DECL_BITFIELD(GBASerializedMulticartFlags, uint32_t);
+DECL_BIT(GBASerializedMulticartFlags, DustSettling, 0);
 
 DECL_BITFIELD(GBASerializedSavedataFlags, uint8_t);
 DECL_BITS(GBASerializedSavedataFlags, FlashState, 0, 2);
@@ -370,7 +393,7 @@ struct GBASerializedState {
 		GBASerializedHWFlags1 flags1;
 		uint8_t lightSample;
 		GBASerializedHWFlags2 flags2;
-		GBASerializedHWFlags3 flags3;
+		GBASerializedUnlCartFlags unlCartFlags;
 		uint32_t sioNextEvent;
 	} hw;
 
@@ -407,8 +430,23 @@ struct GBASerializedState {
 	uint32_t nextIrq;
 	int32_t biosStall;
 
-	uint32_t matrixMappings[16];
-	uint32_t reservedMatrix[2];
+	union {
+		struct {
+			uint32_t mappings[16];
+			uint32_t reserved[2];
+		} matrix2;
+		struct {
+			uint8_t bank;
+			uint8_t offset;
+			uint8_t size;
+			uint8_t sramActive;
+			uint8_t unk;
+			uint8_t currentSize;
+			uint16_t currentOffset;
+			uint32_t settleNextEvent;
+			GBASerializedMulticartFlags flags;
+		} multicart;
+	};
 
 	struct {
 		int8_t chA[16];
diff --git a/src/gba/CMakeLists.txt b/src/gba/CMakeLists.txt
index 01a968a41..71ab7bbb1 100644
--- a/src/gba/CMakeLists.txt
+++ b/src/gba/CMakeLists.txt
@@ -6,6 +6,7 @@ set(SOURCE_FILES
 	cart/ereader.c
 	cart/gpio.c
 	cart/matrix.c
+	cart/unlicensed.c
 	cart/vfame.c
 	cheats.c
 	cheats/codebreaker.c
diff --git a/src/gba/cart/matrix.c b/src/gba/cart/matrix.c
index c594d66b9..9ccbe8832 100644
--- a/src/gba/cart/matrix.c
+++ b/src/gba/cart/matrix.c
@@ -109,7 +109,7 @@ void GBAMatrixSerialize(const struct GBA* gba, struct GBASerializedState* state)
 
 	int i;
 	for (i = 0; i < 16; ++i) {
-		STORE_32(gba->memory.matrix.mappings[i], i << 2, state->matrixMappings);
+		STORE_32(gba->memory.matrix.mappings[i], i << 2, state->matrix2.mappings);
 	}
 }
 
@@ -121,7 +121,7 @@ void GBAMatrixDeserialize(struct GBA* gba, const struct GBASerializedState* stat
 
 	int i;
 	for (i = 0; i < 16; ++i) {
-		LOAD_32(gba->memory.matrix.mappings[i], i << 2, state->matrixMappings);
+		LOAD_32(gba->memory.matrix.mappings[i], i << 2, state->matrix2.mappings);
 		gba->memory.matrix.paddr = gba->memory.matrix.mappings[i];
 		gba->memory.matrix.vaddr = i << 9;
 		_remapMatrix(gba);
diff --git a/src/gba/cart/unlicensed.c b/src/gba/cart/unlicensed.c
new file mode 100644
index 000000000..318ffe891
--- /dev/null
+++ b/src/gba/cart/unlicensed.c
@@ -0,0 +1,219 @@
+/* Copyright (c) 2013-2024 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include <mgba/internal/gba/cart/unlicensed.h>
+
+#include <mgba/internal/arm/macros.h>
+#include <mgba/internal/gba/gba.h>
+#include <mgba/internal/gba/serialize.h>
+#include <mgba-util/vfs.h>
+
+#define MULTI_SETTLE 512
+#define MULTI_BLOCK 0x80000
+#define MULTI_BANK 0x2000000
+
+enum GBMulticartCfgOffset {
+	GBA_MULTICART_CFG_BANK = 0x2,
+	GBA_MULTICART_CFG_OFFSET = 0x3,
+	GBA_MULTICART_CFG_SIZE = 0x4,
+	GBA_MULTICART_CFG_SRAM = 0x5,
+	GBA_MULTICART_CFG_UNK = 0x6,
+};
+
+static void _multicartSettle(struct mTiming* timing, void* context, uint32_t cyclesLate);
+
+void GBAUnlCartInit(struct GBA* gba) {
+	memset(&gba->memory.unl, 0, sizeof(gba->memory.unl));
+}
+
+void GBAUnlCartDetect(struct GBA* gba) {
+	if (!gba->memory.rom) {
+		return;
+	}
+
+	struct GBACartridge* cart = (struct GBACartridge*) gba->memory.rom;
+	if (GBAVFameDetect(&gba->memory.unl.vfame, gba->memory.rom, gba->memory.romSize, gba->romCrc32)) {
+		gba->memory.unl.type = GBA_UNL_CART_VFAME;
+		return;
+	}
+
+	if (memcmp(&cart->id, "AXVJ01", 6) == 0) {
+		if (gba->romVf && gba->romVf->size(gba->romVf) >= 0x04000000) {
+			// Bootleg multicart
+			// TODO: Identify a bit more precisely
+			gba->isPristine = false;
+			GBASavedataInitSRAM(&gba->memory.savedata);
+			gba->memory.unl.type = GBA_UNL_CART_MULTICART;
+
+			gba->romVf->unmap(gba->romVf, gba->memory.rom, gba->memory.romSize);
+			gba->memory.unl.multi.fullSize = gba->romVf->size(gba->romVf);
+			gba->memory.unl.multi.rom = gba->romVf->map(gba->romVf, gba->memory.unl.multi.fullSize, MAP_READ);
+			gba->memory.rom = gba->memory.unl.multi.rom;
+			gba->memory.hw.gpioBase = NULL;
+
+			gba->memory.unl.multi.settle.context = gba;
+			gba->memory.unl.multi.settle.callback = _multicartSettle;
+			gba->memory.unl.multi.settle.name = "GBA Unlicensed Multicart Settle";
+			gba->memory.unl.multi.settle.priority = 0x71;
+		}
+	}
+}
+
+void GBAUnlCartReset(struct GBA* gba) {
+	if (gba->memory.unl.type == GBA_UNL_CART_MULTICART) {
+		gba->memory.unl.multi.bank = 0;
+		gba->memory.unl.multi.offset = 0;
+		gba->memory.unl.multi.size = 0;
+		gba->memory.rom = gba->memory.unl.multi.rom;
+		gba->memory.romSize = GBA_SIZE_ROM0;
+	}
+}
+
+void GBAUnlCartUnload(struct GBA* gba) {
+	if (gba->memory.unl.type == GBA_UNL_CART_MULTICART && gba->romVf) {
+		gba->romVf->unmap(gba->romVf, gba->memory.unl.multi.rom, gba->memory.unl.multi.size);
+		gba->memory.unl.multi.rom = NULL;
+		gba->memory.rom = NULL;
+	}
+}
+
+void GBAUnlCartWriteSRAM(struct GBA* gba, uint32_t address, uint8_t value) {
+	struct GBAUnlCart* unl = &gba->memory.unl;
+
+	switch (unl->type) {
+	case GBA_UNL_CART_VFAME:
+		GBAVFameSramWrite(&unl->vfame, address, value, gba->memory.savedata.data);
+		return;
+	case GBA_UNL_CART_MULTICART:
+		mLOG(GBA_MEM, DEBUG, "Multicart writing SRAM %06X:%02X", address, value);
+		switch (address) {
+		case GBA_MULTICART_CFG_BANK:
+			unl->multi.bank = value >> 4;
+			mTimingDeschedule(&gba->timing, &unl->multi.settle);
+			mTimingSchedule(&gba->timing, &unl->multi.settle, MULTI_SETTLE);
+			break;
+		case GBA_MULTICART_CFG_OFFSET:
+			unl->multi.offset = value & 0x3F;
+			mTimingDeschedule(&gba->timing, &unl->multi.settle);
+			mTimingSchedule(&gba->timing, &unl->multi.settle, MULTI_SETTLE);
+			break;
+		case GBA_MULTICART_CFG_SIZE:
+			unl->multi.size = 0x40 - (value & 0x3F);
+			mTimingDeschedule(&gba->timing, &unl->multi.settle);
+			mTimingSchedule(&gba->timing, &unl->multi.settle, MULTI_SETTLE);
+			break;
+		case GBA_MULTICART_CFG_SRAM:
+			if (value == 0 && unl->multi.sramActive) {
+				unl->multi.sramActive = false;
+			} else if (value == 1 && !unl->multi.sramActive) {
+				unl->multi.sramActive = true;
+			}
+			break;
+		case GBA_MULTICART_CFG_UNK:
+			// TODO: What does this do?
+			unl->multi.unk = value;
+			break;
+		default:
+			break;
+		}
+		break;
+	case GBA_UNL_CART_NONE:
+		break;
+	}
+
+	gba->memory.savedata.data[address & (GBA_SIZE_SRAM - 1)] = value;
+}
+
+static void _multicartSettle(struct mTiming* timing, void* context, uint32_t cyclesLate) {
+	UNUSED(timing);
+	UNUSED(cyclesLate);
+	struct GBA* gba = context;
+	mLOG(GBA_MEM, INFO, "Switching to bank %i offset %i, size %i",
+	     gba->memory.unl.multi.bank, gba->memory.unl.multi.offset, gba->memory.unl.multi.size);
+	size_t offset = gba->memory.unl.multi.bank * (MULTI_BANK >> 2) + gba->memory.unl.multi.offset * (MULTI_BLOCK >> 2);
+	size_t size = gba->memory.unl.multi.size * MULTI_BLOCK;
+	if (offset * 4 >= gba->memory.unl.multi.fullSize || offset * 4 + size > gba->memory.unl.multi.fullSize) {
+		mLOG(GBA_MEM, GAME_ERROR, "Bank switch was out of bounds, %07" PRIz "X + %" PRIz "X > %07" PRIz "X",
+		     offset * 4, size, gba->memory.unl.multi.fullSize);
+		return;
+	}
+	gba->memory.rom = gba->memory.unl.multi.rom + offset;
+	gba->memory.romSize = size;
+}
+
+void GBAUnlCartSerialize(const struct GBA* gba, struct GBASerializedState* state) {
+	GBASerializedUnlCartFlags flags = 0;
+	const struct GBAUnlCart* unl = &gba->memory.unl;
+	switch (unl->type) {
+	case GBA_UNL_CART_NONE:
+		return;
+	case GBA_UNL_CART_VFAME:
+		flags = GBASerializedUnlCartFlagsSetType(flags, GBA_UNL_CART_VFAME);
+		flags = GBASerializedUnlCartFlagsSetSubtype(flags, unl->vfame.cartType);
+		mLOG(GBA_MEM, STUB, "Vast Fame save states are not yet implemented");
+		break;
+	case GBA_UNL_CART_MULTICART:
+		flags = GBASerializedUnlCartFlagsSetType(0, GBA_UNL_CART_MULTICART);
+		state->multicart.bank = unl->multi.bank;
+		state->multicart.offset = unl->multi.offset;
+		state->multicart.size = unl->multi.size;
+		state->multicart.sramActive = unl->multi.sramActive;
+		state->multicart.unk = unl->multi.unk;
+		state->multicart.currentSize = gba->memory.romSize / MULTI_BLOCK;
+		STORE_16((gba->memory.rom - unl->multi.rom) / 0x20000, 0, &state->multicart.currentOffset);
+		STORE_32(unl->multi.settle.when, 0, &state->multicart.settleNextEvent);
+		if (mTimingIsScheduled(&gba->timing, &unl->multi.settle)) {
+			STORE_32(GBASerializedMulticartFlagsFillDustSettling(0), 0, &state->multicart.flags);
+		}
+		break;
+	}
+	STORE_32(flags, 0, &state->hw.unlCartFlags);
+}
+
+void GBAUnlCartDeserialize(struct GBA* gba, const struct GBASerializedState* state) {
+	GBASerializedUnlCartFlags flags;
+	struct GBAUnlCart* unl = &gba->memory.unl;
+
+	LOAD_32(flags, 0, &state->hw.unlCartFlags);
+	enum GBAUnlCartType type = GBASerializedUnlCartFlagsGetType(flags);
+	if (type != unl->type) {
+		mLOG(GBA_STATE, WARN, "Save state expects different bootleg type; not restoring bootleg state");
+		return;
+	}
+
+	uint32_t when;
+	uint32_t offset;
+	size_t size;
+	GBASerializedMulticartFlags multiFlags;
+
+	switch (type) {
+	case GBA_UNL_CART_NONE:
+		return;
+	case GBA_UNL_CART_VFAME:
+		mLOG(GBA_MEM, STUB, "Vast Fame save states are not yet implemented");
+		return;
+	case GBA_UNL_CART_MULTICART:
+		unl->multi.bank = state->multicart.bank;
+		unl->multi.offset = state->multicart.offset;
+		unl->multi.size = state->multicart.size;
+		unl->multi.sramActive = state->multicart.sramActive;
+		unl->multi.unk = state->multicart.unk;
+		size = state->multicart.currentSize * MULTI_BLOCK;
+		LOAD_16(offset, 0, &state->multicart.currentOffset);
+		offset *= 0x20000;
+		if (offset * 4 >= gba->memory.unl.multi.fullSize || offset * 4 + size > gba->memory.unl.multi.fullSize) {
+			mLOG(GBA_STATE, WARN, "Multicart save state has corrupted ROM offset");
+		} else {
+			gba->memory.romSize = size;
+			gba->memory.rom = unl->multi.rom + offset;
+		}
+		LOAD_32(multiFlags, 0, &state->multicart.flags);
+		if (GBASerializedMulticartFlagsIsDustSettling(multiFlags)) {
+			LOAD_32(when, 0, &state->multicart.settleNextEvent);
+			mTimingSchedule(&gba->timing, &unl->multi.settle, when);
+		}
+		break;
+	}
+}
diff --git a/src/gba/cart/vfame.c b/src/gba/cart/vfame.c
index b66b7d756..a45a420c0 100644
--- a/src/gba/cart/vfame.c
+++ b/src/gba/cart/vfame.c
@@ -4,7 +4,7 @@
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-#include <mgba/internal/gba/cart/vfame.h>
+#include <mgba/internal/gba/cart/unlicensed.h>
 
 #include <mgba/internal/gba/gba.h>
 #include <mgba/internal/gba/memory.h>
@@ -60,25 +60,19 @@ static int8_t _modifySramValue(enum GBAVFameCartType type, uint8_t value, int mo
 static uint32_t _modifySramAddress(enum GBAVFameCartType type, uint32_t address, int mode);
 static int _reorderBits(uint32_t value, const uint8_t* reordering, int reorderLength);
 
-void GBAVFameInit(struct GBAVFameCart* cart) {
-	cart->cartType = VFAME_NO;
-	cart->sramMode = -1;
-	cart->romMode = -1;
-	cart->acceptingModeChange = false;
-}
-
-void GBAVFameDetect(struct GBAVFameCart* cart, uint32_t* rom, size_t romSize, uint32_t crc32) {
-	cart->cartType = VFAME_NO;
-
+bool GBAVFameDetect(struct GBAVFameCart* cart, uint32_t* rom, size_t romSize, uint32_t crc32) {
 	// The initialisation code is also present & run in the dumps of Digimon Ruby & Sapphire from hacked/deprotected reprint carts,
 	// which would break if run in "proper" VFame mode so we need to exclude those..
 	if (romSize == 0x2000000) { // the deprotected dumps are 32MB but no real VF games are this size
-		return;
+		return false;
 	}
 
+	bool detected = false;
+
 	// Most games have the same init sequence in the same place
 	// but LOTR/Mo Jie Qi Bing doesn't, probably because it's based on the Kiki KaiKai engine, so just detect based on its title
 	if (memcmp(INIT_SEQUENCE, &rom[0x57], sizeof(INIT_SEQUENCE)) == 0 || memcmp("\0LORD\0WORD\0\0AKIJ", &((struct GBACartridge*) rom)->title, 16) == 0) {
+		detected = true;
 		cart->cartType = VFAME_STANDARD;
 		mLOG(GBA_MEM, INFO, "Vast Fame game detected");
 	}
@@ -87,13 +81,23 @@ void GBAVFameDetect(struct GBAVFameCart* cart, uint32_t* rom, size_t romSize, ui
 	// Their initialisation seems to be identical so the difference must be in the cart HW itself
 	// Other undumped games may have similar differences
 	if (memcmp("George Sango", &((struct GBACartridge*) rom)->title, 12) == 0) {
+		detected = true;
 		cart->cartType = VFAME_GEORGE;
 		mLOG(GBA_MEM, INFO, "George mode");
 	} else if (crc32 == DIGIMON_SAPPHIRE_CHINESE_CRC32) {
 		// Chinese version of Digimon Sapphire; header is identical to the English version which uses the normal reordering
 		// so we have to use some other way to detect it
+		detected = true;
 		cart->cartType = VFAME_ALTERNATE;
 	}
+
+	if (detected) {
+		cart->sramMode = -1;
+		cart->romMode = -1;
+		cart->acceptingModeChange = false;
+	}
+
+	return detected;
 }
 
 // This is not currently being used but would be called on ROM reads
@@ -235,7 +239,6 @@ static uint32_t _patternRightShift2(uint32_t addr) {
 }
 
 void GBAVFameSramWrite(struct GBAVFameCart* cart, uint32_t address, uint8_t value, uint8_t* sramData) {
-	address &= 0x00FFFFFF;
 	// A certain sequence of writes to SRAM FFF8->FFFC can enable or disable "mode change" mode
 	// Currently unknown if these writes have to be sequential, or what happens if you write different values, if anything
 	if (address >= 0xFFF8 && address <= 0xFFFC) {
diff --git a/src/gba/gba.c b/src/gba/gba.c
index 6b833838e..1b84038ae 100644
--- a/src/gba/gba.c
+++ b/src/gba/gba.c
@@ -140,6 +140,9 @@ static void GBAInit(void* cpu, struct mCPUComponent* component) {
 
 void GBAUnloadROM(struct GBA* gba) {
 	GBAMemoryClearAGBPrint(gba);
+	if (gba->memory.unl.type) {
+		GBAUnlCartUnload(gba);
+	}
 	if (gba->memory.rom && !gba->isPristine) {
 		if (gba->yankedRomSize) {
 			gba->yankedRomSize = 0;
@@ -492,7 +495,7 @@ bool GBALoadROM(struct GBA* gba, struct VFile* vf) {
 		gba->cpu->memory.setActiveRegion(gba->cpu, gba->cpu->gprs[ARM_PC]);
 	}
 	GBAHardwareInit(&gba->memory.hw, &((uint16_t*) gba->memory.rom)[GPIO_REG_DATA >> 1]);
-	GBAVFameDetect(&gba->memory.vfame, gba->memory.rom, gba->memory.romSize, gba->romCrc32);
+	GBAUnlCartDetect(gba);
 	// TODO: error check
 	return true;
 }
diff --git a/src/gba/io.c b/src/gba/io.c
index cb6058f7f..a72171c1f 100644
--- a/src/gba/io.c
+++ b/src/gba/io.c
@@ -1033,6 +1033,7 @@ void GBAIOSerialize(struct GBA* gba, struct GBASerializedState* state) {
 	STORE_32(gba->bus, 0, &state->bus);
 
 	GBAHardwareSerialize(&gba->memory.hw, state);
+	GBAUnlCartSerialize(gba, state);
 }
 
 void GBAIODeserialize(struct GBA* gba, const struct GBASerializedState* state) {
@@ -1082,4 +1083,5 @@ void GBAIODeserialize(struct GBA* gba, const struct GBASerializedState* state) {
 	GBADMARecalculateCycles(gba);
 	GBADMAUpdate(gba);
 	GBAHardwareDeserialize(&gba->memory.hw, state);
+	GBAUnlCartDeserialize(gba, state);
 }
diff --git a/src/gba/memory.c b/src/gba/memory.c
index 87e31f746..53d0f7cc9 100644
--- a/src/gba/memory.c
+++ b/src/gba/memory.c
@@ -93,7 +93,7 @@ void GBAMemoryInit(struct GBA* gba) {
 	gba->memory.iwram = &gba->memory.wram[GBA_SIZE_EWRAM >> 2];
 
 	GBADMAInit(gba);
-	GBAVFameInit(&gba->memory.vfame);
+	GBAUnlCartInit(gba);
 
 	gba->memory.ereader.p = gba;
 	gba->memory.ereader.dots = NULL;
@@ -139,6 +139,7 @@ void GBAMemoryReset(struct GBA* gba) {
 	}
 
 	GBADMAReset(gba);
+	GBAUnlCartReset(gba);
 	memset(&gba->memory.matrix, 0, sizeof(gba->memory.matrix));
 }
 
@@ -411,7 +412,7 @@ static void GBASetActiveRegion(struct ARMCore* cpu, uint32_t address) {
 	wait += waitstatesRegion[address >> BASE_OFFSET]; \
 	if ((address & (GBA_SIZE_ROM0 - 4)) < memory->romSize) { \
 		LOAD_32(value, address & (GBA_SIZE_ROM0 - 4), memory->rom); \
-	} else if (memory->vfame.cartType) { \
+	} else if (memory->unl.type == GBA_UNL_CART_VFAME) { \
 		value = GBAVFameGetPatternValue(address, 32); \
 	} else { \
 		mLOG(GBA_MEM, GAME_ERROR, "Out of bounds ROM Load32: 0x%08X", address); \
@@ -576,7 +577,7 @@ uint32_t GBALoad16(struct ARMCore* cpu, uint32_t address, int* cycleCounter) {
 		wait = memory->waitstatesNonseq16[address >> BASE_OFFSET];
 		if ((address & (GBA_SIZE_ROM0 - 2)) < memory->romSize) {
 			LOAD_16(value, address & (GBA_SIZE_ROM0 - 2), memory->rom);
-		} else if (memory->vfame.cartType) {
+		} else if (memory->unl.type == GBA_UNL_CART_VFAME) {
 			value = GBAVFameGetPatternValue(address, 16);
 		} else if ((address & (GBA_SIZE_ROM0 - 2)) >= AGB_PRINT_BASE) {
 			uint32_t agbPrintAddr = address & 0x00FFFFFF;
@@ -601,7 +602,7 @@ uint32_t GBALoad16(struct ARMCore* cpu, uint32_t address, int* cycleCounter) {
 			value = GBACartEReaderRead(&memory->ereader, address);
 		} else if ((address & (GBA_SIZE_ROM0 - 2)) < memory->romSize) {
 			LOAD_16(value, address & (GBA_SIZE_ROM0 - 2), memory->rom);
-		} else if (memory->vfame.cartType) {
+		} else if (memory->unl.type == GBA_UNL_CART_VFAME) {
 			value = GBAVFameGetPatternValue(address, 16);
 		} else {
 			mLOG(GBA_MEM, GAME_ERROR, "Out of bounds ROM Load16: 0x%08X", address);
@@ -692,7 +693,7 @@ uint32_t GBALoad8(struct ARMCore* cpu, uint32_t address, int* cycleCounter) {
 		wait = memory->waitstatesNonseq16[address >> BASE_OFFSET];
 		if ((address & (GBA_SIZE_ROM0 - 1)) < memory->romSize) {
 			value = ((uint8_t*) memory->rom)[address & (GBA_SIZE_ROM0 - 1)];
-		} else if (memory->vfame.cartType) {
+		} else if (memory->unl.type == GBA_UNL_CART_VFAME) {
 			value = GBAVFameGetPatternValue(address, 8);
 		} else {
 			mLOG(GBA_MEM, GAME_ERROR, "Out of bounds ROM Load8: 0x%08X", address);
@@ -1056,8 +1057,8 @@ void GBAStore8(struct ARMCore* cpu, uint32_t address, int8_t value, int* cycleCo
 		} else if (memory->savedata.type == GBA_SAVEDATA_FLASH512 || memory->savedata.type == GBA_SAVEDATA_FLASH1M) {
 			GBASavedataWriteFlash(&memory->savedata, address, value);
 		} else if (memory->savedata.type == GBA_SAVEDATA_SRAM) {
-			if (memory->vfame.cartType) {
-				GBAVFameSramWrite(&memory->vfame, address, value, memory->savedata.data);
+			if (memory->unl.type) {
+				GBAUnlCartWriteSRAM(gba, address & 0xFFFF, value);
 			} else {
 				memory->savedata.data[address & (GBA_SIZE_SRAM - 1)] = value;
 			}
diff --git a/src/gba/overrides.c b/src/gba/overrides.c
index a63616e61..1e3e9e6fc 100644
--- a/src/gba/overrides.c
+++ b/src/gba/overrides.c
@@ -377,6 +377,12 @@ void GBAOverrideApplyDefaults(struct GBA* gba, const struct Configuration* overr
 	struct GBACartridgeOverride override = { .idleLoop = GBA_IDLE_LOOP_NONE };
 	const struct GBACartridge* cart = (const struct GBACartridge*) gba->memory.rom;
 	if (cart) {
+		if (gba->memory.unl.type == GBA_UNL_CART_MULTICART) {
+			override.savetype = GBA_SAVEDATA_SRAM;
+			GBAOverrideApply(gba, &override);
+			return;
+		}
+
 		memcpy(override.id, &cart->id, sizeof(override.id));
 
 		static const uint32_t pokemonTable[] = {
diff --git a/src/gba/serialize.c b/src/gba/serialize.c
index 5eabaedea..9d6130385 100644
--- a/src/gba/serialize.c
+++ b/src/gba/serialize.c
@@ -32,8 +32,17 @@ void GBASerialize(struct GBA* gba, struct GBASerializedState* state) {
 	STORE_64LE(gba->timing.globalCycles, 0, &state->globalCycles);
 
 	if (gba->memory.rom) {
-		state->id = ((struct GBACartridge*) gba->memory.rom)->id;
-		memcpy(state->title, ((struct GBACartridge*) gba->memory.rom)->title, sizeof(state->title));
+		switch (gba->memory.unl.type) {
+		case GBA_UNL_CART_NONE:
+		case GBA_UNL_CART_VFAME:
+			state->id = ((struct GBACartridge*) gba->memory.rom)->id;
+			memcpy(state->title, ((struct GBACartridge*) gba->memory.rom)->title, sizeof(state->title));
+			break;
+		case GBA_UNL_CART_MULTICART:
+			state->id = ((struct GBACartridge*) gba->memory.unl.multi.rom)->id;
+			memcpy(state->title, ((struct GBACartridge*) gba->memory.unl.multi.rom)->title, sizeof(state->title));
+			break;
+		}
 	} else {
 		state->id = 0;
 		memset(state->title, 0, sizeof(state->title));
@@ -106,9 +115,21 @@ bool GBADeserialize(struct GBA* gba, const struct GBASerializedState* state) {
 			error = true;
 		}
 	}
-	if (gba->memory.rom && (state->id != ((struct GBACartridge*) gba->memory.rom)->id || memcmp(state->title, ((struct GBACartridge*) gba->memory.rom)->title, sizeof(state->title)))) {
-		mLOG(GBA_STATE, WARN, "Savestate is for a different game");
-		error = true;
+	if (gba->memory.rom) {
+		struct GBACartridge* cart;
+		switch (gba->memory.unl.type) {
+		case GBA_UNL_CART_NONE:
+		case GBA_UNL_CART_VFAME:
+			cart = (struct GBACartridge*) gba->memory.rom;
+			break;
+		case GBA_UNL_CART_MULTICART:
+			cart = (struct GBACartridge*) gba->memory.unl.multi.rom;
+			break;
+		}
+		if (state->id != cart->id || memcmp(state->title, cart->title, sizeof(state->title))) {
+			mLOG(GBA_STATE, WARN, "Savestate is for a different game");
+			error = true;
+		}
 	} else if (!gba->memory.rom && state->id != 0) {
 		mLOG(GBA_STATE, WARN, "Savestate is for a game, but no game loaded");
 		error = true;