diff --git a/asm/main.s b/asm/main_s.s
similarity index 68%
rename from asm/main.s
rename to asm/main_s.s
index a685ce2de..01992fb26 100644
--- a/asm/main.s
+++ b/asm/main_s.s
@@ -3,207 +3,11 @@
 	.public ov60_021EB030
 	.public ov36_021E5C04
 
-	.bss
-
-gBacklightTop:
-	.space 0x4
-
+	.public gBacklightTop
 	.public _02111864
-_02111864:
-	.space 0x4
-
-_02111868:
-	.space 0x1C
-
+	.public _02111868
 	.text
 
-	; Entry point
-	thumb_func_start NitroMain
-NitroMain: ; 0x02000CA4
-	push {r3, r4, r5, r6, r7, lr}
-	bl InitSystemForTheGame
-	bl InitGraphicMemory
-	bl InitKeypadAndTouchpad
-	mov r0, #0
-	bl sub_0201A4B0
-	ldr r0, _02000E48 ; =gBacklightTop
-	mov r1, #0
-	bl PM_GetBackLight
-	bl sub_02026E30
-	bl GF_InitRTCWork
-	bl Main_ResetOverlayManager
-	bl sub_02002CA8
-	mov r0, #0
-	mov r1, #3
-	bl sub_02002CEC
-	mov r0, #1
-	mov r1, #3
-	bl sub_02002CEC
-	mov r0, #3
-	add r1, r0, #0
-	bl sub_02002CEC
-	mov r1, #0
-	; Note to decompiler: the -ipa file switch causes most file-local symbol access to be compiled relative to the top symbol in that section. This is buggy in practice.
-	ldr r0, _02000E4C ; =_0211868-8
-	mvn r1, r1
-	str r1, [r0, #0x18]
-	bl SaveBlock2_new
-	ldr r1, _02000E4C ; =_0211868-8
-	str r0, [r1, #0x20]
-	bl sub_02005D00
-	ldr r0, _02000E4C ; =_0211868-8
-	ldr r0, [r0, #0x20]
-	bl Sav2_Chatot_get
-	add r4, r0, #0
-	ldr r0, _02000E4C ; =_0211868-8
-	ldr r0, [r0, #0x20]
-	bl Sav2_PlayerData_GetOptionsAddr
-	add r1, r0, #0
-	add r0, r4, #0
-	bl InitSoundData
-	bl Init_Timer3
-	mov r0, #3
-	bl sub_02039FFC
-	cmp r0, #3
-	bne _02000D2C
-	mov r0, #3
-	mov r1, #0
-	bl ShowWFCUserInfoWarning
-_02000D2C:
-	ldr r0, _02000E4C ; =_0211868-8
-	ldr r0, [r0, #0x20]
-	bl sub_020274D0
-	cmp r0, #0
-	bne _02000D40
-	mov r0, #0
-	bl ShowSaveDataReadError
-	b _02000D82
-_02000D40:
-	; static inline int OS_GetResetParameter();
-	ldr r0, _02000E50 ; =0x027FFC20
-	ldr r0, [r0]
-	cmp r0, #0
-	beq _02000D4E
-	cmp r0, #1
-	beq _02000D5E
-	b _02000D7E
-_02000D4E:
-	; Title Demo
-	ldr r0, _02000E4C ; =_0211868-8
-	mov r1, #0
-	str r1, [r0, #0x1c]
-	ldr r0, _02000E54 ; =SDK_OVERLAY_OVY_60_ID
-	ldr r1, _02000E58 ; =ov60_021EB030
-	bl RegisterMainOverlay
-	b _02000D82
-_02000D5E:
-	; Reset transition?
-	mov r0, #0
-	add r1, r0, #0
-	bl sub_0200FBF4
-	mov r0, #1
-	mov r1, #0
-	bl sub_0200FBF4
-	ldr r0, _02000E4C ; =_0211868-8
-	mov r1, #1
-	str r1, [r0, #0x1c]
-	ldr r0, _02000E5C ; =SDK_OVERLAY_OVY_36_ID
-	ldr r1, _02000E60 ; =ov36_021E5C04
-	bl RegisterMainOverlay
-	b _02000D82
-_02000D7E:
-	bl GF_AssertFail
-_02000D82:
-	ldr r0, _02000E64 ; =gSystem
-	mov r1, #1
-	str r1, [r0, #0x70]
-	mov r1, #0
-	str r1, [r0, #0x30]
-	bl InitializeMainRNG
-	bl sub_0200B528
-	bl sub_02018380
-	ldr r0, _02000E4C ; =_0211864-4
-	mov r1, #0
-	str r1, [r0, #4]
-	bl OS_InitTick
-	mov r7, #0xc3
-	ldr r6, _02000E68 ; =gSystem + 0x60
-	ldr r4, _02000E64 ; =gSystem
-	mov r5, #0
-	lsl r7, r7, #2
-_02000DAC:
-	bl sub_02000F60
-	bl HandleDSLidAction
-	bl ReadKeypadAndTouchpad
-	mov r0, #0xc3
-	ldr r1, [r4, #0x38]
-	lsl r0, r0, #2
-	and r0, r1
-	cmp r0, r7
-	bne _02000DD0
-	ldrb r0, [r6, #0xc]
-	cmp r0, #0
-	bne _02000DD0
-	mov r0, #0
-	bl DoSoftReset
-_02000DD0:
-	bl sub_02036144
-	cmp r0, #0
-	beq _02000E08
-	bl sub_02000F60
-	bl OS_GetTick
-	bl Main_RunOverlayManager
-	bl OS_GetTick
-	ldr r0, [r4, #0x18]
-	bl sub_0201F880
-	ldr r0, [r4, #0x24]
-	bl sub_0201F880
-	ldr r0, [r4, #0x30]
-	cmp r0, #0
-	bne _02000E08
-	mov r0, #1
-	add r1, r0, #0
-	bl OS_WaitIrq
-	ldr r0, [r4, #0x2c]
-	add r0, r0, #1
-	str r0, [r4, #0x2c]
-_02000E08:
-	bl GF_RTC_UpdateOnFrame
-	bl sub_020183B0
-	bl sub_02026E60
-	ldr r0, [r4, #0x24]
-	bl sub_0201F880
-	mov r0, #1
-	add r1, r0, #0
-	bl OS_WaitIrq
-	ldr r0, [r4, #0x2c]
-	add r0, r0, #1
-	str r0, [r4, #0x2c]
-	str r5, [r4, #0x30]
-	bl sub_0200B594
-	bl sub_0200FB2C
-	ldr r1, [r4]
-	cmp r1, #0
-	beq _02000E3C
-	ldr r0, [r4, #4]
-	blx r1
-_02000E3C:
-	bl DoSoundUpdateFrame
-	ldr r0, [r4, #0x20]
-	bl sub_0201F880
-	b _02000DAC
-	.balign 4, 0
-_02000E48: .word gBacklightTop
-_02000E4C: .word gBacklightTop
-_02000E50: .word 0x027FFC20
-_02000E54: .word SDK_OVERLAY_OVY_60_ID
-_02000E58: .word ov60_021EB030
-_02000E5C: .word SDK_OVERLAY_OVY_36_ID
-_02000E60: .word ov36_021E5C04
-_02000E64: .word gSystem
-_02000E68: .word gSystem + 0x60
-	thumb_func_end NitroMain
-
 	thumb_func_start Main_ResetOverlayManager
 Main_ResetOverlayManager: ; 0x02000E6C
 	mov r2, #0
diff --git a/include/font.h b/include/font.h
index 3328635e8..dd60c84c0 100644
--- a/include/font.h
+++ b/include/font.h
@@ -4,5 +4,7 @@
 typedef u8 FontID;
 
 u32 FontI_GetGlyphWidth(FontID fontId, u16 character);
+void sub_02002CA8(void);
+void sub_02002CEC(int a0, HeapID heapId);
 
 #endif //POKEHEARTGOLD_FONT_H
diff --git a/include/main.h b/include/main.h
index 7831511e1..17f4f42a8 100644
--- a/include/main.h
+++ b/include/main.h
@@ -2,9 +2,17 @@
 #define POKEHEARTGOLD_MAIN_H
 
 #include "overlay_manager.h"
+#include "save.h"
+
+struct UnkStruct_02111868_sub {
+    int unk_00;
+    u32 unk_04;
+    SAVEDATA *savedata;
+};
 
 void Main_ResetOverlayManager(void);
 void RegisterMainOverlay(FSOverlayID overlayId, const OVY_MGR_TEMPLATE *template);
 void InitializeMainRNG(void);
+void HandleDSLidAction(void);
 
 #endif //POKEHEARTGOLD_MAIN_H
diff --git a/include/sav_chatot.h b/include/sav_chatot.h
new file mode 100644
index 000000000..be68a0da7
--- /dev/null
+++ b/include/sav_chatot.h
@@ -0,0 +1,10 @@
+#ifndef POKEHEARTGOLD_SAV_CHATOT_H
+#define POKEHEARTGOLD_SAV_CHATOT_H
+
+#include "save.h"
+
+typedef struct SOUND_CHATOT SOUND_CHATOT;
+
+SOUND_CHATOT *Sav2_Chatot_get(SAVEDATA *saveData);
+
+#endif //POKEHEARTGOLD_SAV_CHATOT_H
diff --git a/include/save.h b/include/save.h
index 77f476d82..fd85b1b55 100644
--- a/include/save.h
+++ b/include/save.h
@@ -49,10 +49,12 @@
 #ifndef PM_ASM
 typedef struct SaveBlock2 SAVEDATA;
 
+SAVEDATA *SaveBlock2_new(void);
 void *SavArray_get(SAVEDATA *save, int idx);
 const void *SavArray_const_get(const SAVEDATA *save, int idx);
 void SaveSubstruct_UpdateCRC(int idx);
 BOOL SaveSubstruct_AssertCRC(int idx);
+BOOL sub_020274D0(SAVEDATA *save);
 #endif //PM_ASM
 
 #endif //POKEHEARTGOLD_SAVE_H
diff --git a/include/save_data_read_error.h b/include/save_data_read_error.h
new file mode 100644
index 000000000..2d0f6ac39
--- /dev/null
+++ b/include/save_data_read_error.h
@@ -0,0 +1,6 @@
+#ifndef POKEHEARTGOLD_SAVE_DATA_READ_ERROR_H
+#define POKEHEARTGOLD_SAVE_DATA_READ_ERROR_H
+
+void ShowSaveDataReadError(int a0);
+
+#endif //POKEHEARTGOLD_SAVE_DATA_READ_ERROR_H
diff --git a/include/sound_02004A44.h b/include/sound_02004A44.h
new file mode 100644
index 000000000..37aeb79a1
--- /dev/null
+++ b/include/sound_02004A44.h
@@ -0,0 +1,6 @@
+#ifndef POKEHEARTGOLD_SOUND_02004A44_H
+#define POKEHEARTGOLD_SOUND_02004A44_H
+
+void sub_02005D00(void);
+
+#endif //POKEHEARTGOLD_SOUND_02004A44_H
diff --git a/include/sound_chatot.h b/include/sound_chatot.h
index a66ce730a..46c8ec972 100644
--- a/include/sound_chatot.h
+++ b/include/sound_chatot.h
@@ -1,7 +1,7 @@
 #ifndef POKEHEARTGOLD_SOUND_CHATOT_H
 #define POKEHEARTGOLD_SOUND_CHATOT_H
 
-typedef struct SOUND_CHATOT SOUND_CHATOT;
+#include "sav_chatot.h"
 
 void ChatotSoundMain(void);
 extern void PlayCryEx(u32, u16, u32, u32, u32, u8);
diff --git a/include/system.h b/include/system.h
index 88e517039..92e037bf3 100644
--- a/include/system.h
+++ b/include/system.h
@@ -35,9 +35,16 @@ struct System {
     u8 unk67;
     u8 softResetDisabled;
     u8 padding_69[3]; // nice
-    s32 unk6C;
+    u8 unk6C;
+    int unk70;
 };
 
 extern struct System gSystem;
 
+void InitSystemForTheGame(void);
+void InitGraphicMemory(void);
+void InitKeypadAndTouchpad(void);
+void sub_0201A4B0(int a0);
+void ReadKeypadAndTouchpad(void);
+
 #endif //POKEHEARTGOLD_SYSTEM_H
diff --git a/include/timer_3.h b/include/timer_3.h
new file mode 100644
index 000000000..1bb1532d8
--- /dev/null
+++ b/include/timer_3.h
@@ -0,0 +1,6 @@
+#ifndef POKEHEARTGOLD_TIMER_3_H
+#define POKEHEARTGOLD_TIMER_3_H
+
+void Init_Timer3(void);
+
+#endif //POKEHEARTGOLD_TIMER_3_H
diff --git a/include/unk_0200B150.h b/include/unk_0200B150.h
new file mode 100644
index 000000000..eea9c0b9a
--- /dev/null
+++ b/include/unk_0200B150.h
@@ -0,0 +1,7 @@
+#ifndef POKEHEARTGOLD_UNK_0200B150_H
+#define POKEHEARTGOLD_UNK_0200B150_H
+
+void sub_0200B528(void);
+void sub_0200B594(void);
+
+#endif //POKEHEARTGOLD_UNK_0200B150_H
diff --git a/include/unk_0200FA24.h b/include/unk_0200FA24.h
new file mode 100644
index 000000000..415c6c5c9
--- /dev/null
+++ b/include/unk_0200FA24.h
@@ -0,0 +1,7 @@
+#ifndef POKEHEARTGOLD_UNK_0200FA24_H
+#define POKEHEARTGOLD_UNK_0200FA24_H
+
+void sub_0200FBF4(int a0, int a1);
+void sub_0200FB2C(void);
+
+#endif //POKEHEARTGOLD_UNK_0200FA24_H
diff --git a/include/unk_02018380.h b/include/unk_02018380.h
new file mode 100644
index 000000000..5b38c6b0a
--- /dev/null
+++ b/include/unk_02018380.h
@@ -0,0 +1,7 @@
+#ifndef POKEHEARTGOLD_UNK_02018380_H
+#define POKEHEARTGOLD_UNK_02018380_H
+
+void sub_02018380(void);
+void sub_020183B0(void);
+
+#endif //POKEHEARTGOLD_UNK_02018380_H
diff --git a/include/unk_0201F79C.h b/include/unk_0201F79C.h
new file mode 100644
index 000000000..e1f500afd
--- /dev/null
+++ b/include/unk_0201F79C.h
@@ -0,0 +1,6 @@
+#ifndef POKEHEARTGOLD_UNK_0201F79C_H
+#define POKEHEARTGOLD_UNK_0201F79C_H
+
+void sub_0201F880(void *a0);
+
+#endif //POKEHEARTGOLD_UNK_0201F79C_H
diff --git a/include/unk_02026E30.h b/include/unk_02026E30.h
new file mode 100644
index 000000000..a7c68214b
--- /dev/null
+++ b/include/unk_02026E30.h
@@ -0,0 +1,7 @@
+#ifndef POKEHEARTGOLD_UNK_02026E30_H
+#define POKEHEARTGOLD_UNK_02026E30_H
+
+void sub_02026E30(void);
+void sub_02026E60(void);
+
+#endif //POKEHEARTGOLD_UNK_02026E30_H
diff --git a/include/unk_02035900.h b/include/unk_02035900.h
new file mode 100644
index 000000000..a0c89e48e
--- /dev/null
+++ b/include/unk_02035900.h
@@ -0,0 +1,6 @@
+#ifndef POKEHEARTGOLD_UNK_02035900_H
+#define POKEHEARTGOLD_UNK_02035900_H
+
+BOOL sub_02036144(void);
+
+#endif //POKEHEARTGOLD_UNK_02035900_H
diff --git a/include/unk_02037C94.h b/include/unk_02037C94.h
index ff59830e3..564bf2bdf 100644
--- a/include/unk_02037C94.h
+++ b/include/unk_02037C94.h
@@ -2,5 +2,6 @@
 #define POKEHEARTGOLD_UNK_02037C94_H
 
 BOOL sub_02037D78(void);
+int sub_02039FFC(int a0);
 
 #endif //POKEHEARTGOLD_UNK_02037C94_H
diff --git a/include/wfc_user_info_warning.h b/include/wfc_user_info_warning.h
new file mode 100644
index 000000000..2ef53bf03
--- /dev/null
+++ b/include/wfc_user_info_warning.h
@@ -0,0 +1,6 @@
+#ifndef POKEHEARTGOLD_WFC_USER_INFO_WARNING_H
+#define POKEHEARTGOLD_WFC_USER_INFO_WARNING_H
+
+void ShowWFCUserInfoWarning(int a0, int a1);
+
+#endif //POKEHEARTGOLD_WFC_USER_INFO_WARNING_H
diff --git a/lib/include/nitro/os/reset.h b/lib/include/nitro/os/reset.h
index c808a5b8b..1423f3311 100644
--- a/lib/include/nitro/os/reset.h
+++ b/lib/include/nitro/os/reset.h
@@ -16,4 +16,8 @@ void OS_ResetSystem(u32 parameter);
 void OS_ResetSystem(void);
 #endif
 
+static inline u32 OS_GetResetParameter(void) {
+    return *(u32 *)HW_RESET_PARAMETER_BUF;
+}
+
 #endif //NITRO_OS_RESET_H
diff --git a/main.lsf b/main.lsf
index 62a815477..c87588908 100644
--- a/main.lsf
+++ b/main.lsf
@@ -11,6 +11,7 @@ Static main
 	StackSize 0 2048
 	Object pm_version.o
 	Object main.o
+	Object main_s.o
 	Object list_menu.o
 	Object unk_02001AF4.o
 	Object string_util.o
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 000000000..721da31d4
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,124 @@
+#include "main.h"
+#include "system.h"
+#include "gf_rtc.h"
+#include "sound.h"
+#include "sound_02004A44.h"
+#include "player_data.h"
+#include "unk_02026E30.h"
+#include "font.h"
+#include "timer_3.h"
+#include "unk_02037C94.h"
+#include "wfc_user_info_warning.h"
+#include "save_data_read_error.h"
+#include "unk_0200FA24.h"
+#include "unk_0200B150.h"
+#include "unk_02018380.h"
+#include "unk_02035900.h"
+#include "unk_0201F79C.h"
+
+FS_EXTERN_OVERLAY(OVY_60);
+FS_EXTERN_OVERLAY(OVY_36);
+
+extern const OVY_MGR_TEMPLATE ov60_021EB030;
+extern const OVY_MGR_TEMPLATE ov36_021E5C04;
+
+struct UnkStruct_02111868 {
+    FSOverlayID mainOverlayId;
+    OVY_MANAGER *overlayManager;
+    FSOverlayID queuedMainOverlayId;
+    const OVY_MGR_TEMPLATE *queuedMainOverlayTemplate;
+    struct UnkStruct_02111868_sub unk_10;
+};
+
+int _02111864;
+PMBackLightSwitch gBacklightTop;
+struct UnkStruct_02111868 _02111868;
+
+void sub_02000F60(void);
+void DoSoftReset(int a0);
+void Main_RunOverlayManager(void);
+
+void NitroMain(void) {
+    InitSystemForTheGame();
+    InitGraphicMemory();
+    InitKeypadAndTouchpad();
+    sub_0201A4B0(0);
+    PM_GetBackLight(&gBacklightTop, NULL);
+    sub_02026E30();
+    GF_InitRTCWork();
+    Main_ResetOverlayManager();
+    sub_02002CA8();
+    sub_02002CEC(0, 3);
+    sub_02002CEC(1, 3);
+    sub_02002CEC(3, 3);
+    _02111868.unk_10.unk_00 = -1;
+    _02111868.unk_10.savedata = SaveBlock2_new();
+    sub_02005D00();
+    InitSoundData(Sav2_Chatot_get(_02111868.unk_10.savedata), Sav2_PlayerData_GetOptionsAddr(_02111868.unk_10.savedata));
+    Init_Timer3();
+    if (sub_02039FFC(3) == 3) {
+        ShowWFCUserInfoWarning(3, 0);
+    }
+    if (!sub_020274D0(_02111868.unk_10.savedata)) {
+        ShowSaveDataReadError(0);
+    } else {
+        switch (OS_GetResetParameter()) {
+        case 0:
+            _02111868.unk_10.unk_04 = 0;
+            RegisterMainOverlay(FS_OVERLAY_ID(OVY_60), &ov60_021EB030);
+            break;
+        case 1:
+            sub_0200FBF4(0, 0);
+            sub_0200FBF4(1, 0);
+            _02111868.unk_10.unk_04 = 1;
+            RegisterMainOverlay(FS_OVERLAY_ID(OVY_36), &ov36_021E5C04);
+            break;
+        default:
+            GF_ASSERT(0);
+            break;
+        }
+    }
+    gSystem.unk70 = 1;
+    gSystem.unk30 = 0;
+    InitializeMainRNG();
+    sub_0200B528();
+    sub_02018380();
+    _02111864 = 0;
+    OS_InitTick();
+    while (1) {
+        sub_02000F60();
+        HandleDSLidAction();
+        ReadKeypadAndTouchpad();
+        if ((gSystem.heldKeysRaw & (PAD_BUTTON_START | PAD_BUTTON_SELECT | PAD_BUTTON_L | PAD_BUTTON_R)) == (PAD_BUTTON_START | PAD_BUTTON_SELECT | PAD_BUTTON_L | PAD_BUTTON_R)) {
+            if (!gSystem.unk6C) {
+                DoSoftReset(0); // no return
+            }
+        }
+        if (sub_02036144()) {
+            sub_02000F60();
+            OS_GetTick();
+            Main_RunOverlayManager();
+            OS_GetTick();
+            sub_0201F880(gSystem.unk18);
+            sub_0201F880(gSystem.unk24);
+            if (!gSystem.unk30) {
+                OS_WaitIrq(TRUE, OS_IE_VBLANK);
+                gSystem.unk2C++;
+            }
+        }
+        GF_RTC_UpdateOnFrame();
+        sub_020183B0();
+        sub_02026E60();
+        sub_0201F880(gSystem.unk24);
+        OS_WaitIrq(TRUE, OS_IE_VBLANK);
+        gSystem.unk2C++;
+        gSystem.unk30 = 0;
+        sub_0200B594();
+        sub_0200FB2C();
+        if (gSystem.vBlankIntr != NULL) {
+            gSystem.vBlankIntr(gSystem.vBlankIntrArg);
+        }
+        DoSoundUpdateFrame();
+        sub_0201F880(gSystem.unk20);
+    }
+}