Zettai Muteki Raijin-Oh: Zettai Muteki Raijin-Oh - Continue Hack (J / E)

Continue hack for the games Absolute Invincible Raijin-Oh (E) and Zettai Muteki Raijinou (J).

This hack allows you to continue the game infinitely when you die. The story screen is only shown once at the beginning.

The package has following contents: IPS patch for the original Japanese ROM, IPS patch for the translated English ROM and a manual where the disassembling details of the hack are explained (Format: TXT, ODT & PDF).

*************************************************
*** GameBoy ROM Hack for infinitive continues ***
*************************************************

Game: Absolute Invincible Raijin-Oh
Zettai Muteki Raijinou
Hack by blackdrake
Version: July, 23th 2009

== Abstract ==

This hack allows you to continue infinitely without returning to round 1.

== Hexeditor patch summary ==

+-----------------------------------------------------------------------------------------+
|ROM offset English ROM Japanese ROM |
+-----------------------------------------------------------------------------------------+
|0x014e Old C1 31 Old F5 30 |
|0x014e New C9 DE New FD DD |
| |
|0x0b51 Old AF CD A4 2F CD 16 05 3E 01 EA 04 D1 |
|0x0b51 New CD 94 4E 00 00 00 00 00 00 00 00 00 |
| |
|0x8e92 Old 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
|0x8e92 New 18 0F FA 04 D1 FE 00 C0 CD ED 4E 3E 01 EA 04 D1 C9 |
| |
|0x8eeb Old 00 00 00 00 00 00 00 00 00 00 00 |
|0x8eeb New 18 09 3E 00 CD A4 2F CD 16 05 C9 |
+-----------------------------------------------------------------------------------------+

== Disassembling explaination ==

- Original state -

0b51 is called at two places and is the action after "Start" was pressed - so
the game begins here.

+-----------------------------------------------------------------------------------------+
|ROM offset BUS offset Machine code Assembler code Comment |
+-----------------------------------------------------------------------------------------+
|0x0b51 0b51 AF XOR A Set A=0 (A = A XOR A = 0). If this |
| is replaced with NOP (00h) then |
| you'll hear a part of the winning |
| melody when the story appears. |
|0x0b52 0b52 CD A4 2F CALL 2FA4h Stop the music |
|0x0b55 0b55 CD 16 05 CALL 0516h Show the story screen |
|0x0b58 0b58 3E 01 LD A,01h Load value 01 |
|0x0b5a 0b5a EA 04 D1 LD (D104h),A Set it as round counter |
+-----------------------------------------------------------------------------------------+

The BUS areas 4e92..4ea2 (ROM: 0x8e92..0x8ea2) and 4eeb..4ef5 (ROM: 0x8eeb..0x8ef5) are
filled with NOPs (00h). So we can insert some code there because there are no actions
performed. But that does not mean, that the program counter will never reach these areas!

- Part 1 -

In the original code the sound is stopped (A=0), the story is shown and then the round
counter at offset D104h is set to 1. We have to insert some code, but we have not enough
space, so we make a CALL to a free space in the ROM.

+-----------------------------------------------------------------------------------------+
|ROM offset BUS offset Machine code Assembler code Comment |
+-----------------------------------------------------------------------------------------+
|0x0b51 0b51 CD 94 4E CALL 4E94h Jump to our inserted part and then |
| return. |
|0x0b54 0b54 00 NOP Do nothing |
|0x0b55 0b55 00 NOP Do nothing |
|0x0b56 0b56 00 NOP Do nothing |
|0x0b57 0b57 00 NOP Do nothing |
|0x0b58 0b58 00 NOP Do nothing |
|0x0b59 0b59 00 NOP Do nothing |
|0x0b5a 0b5a 00 NOP Do nothing |
|0x0b5b 0b5b 00 NOP Do nothing |
|0x0b5c 0b5c 00 NOP Do nothing |
+-----------------------------------------------------------------------------------------+

- Part 2 -

Now overwrite some hopefully unused NOPs for the insertion of the additional decision
of the round counter. The round counter at offset D104 has the default value 0.
If it is 0, initialize it with 1 and show the story screen. If it is not null, we go
back and let the user play the game another time without story screen and without
reset of the round counter.

+-----------------------------------------------------------------------------------------+
|ROM offset BUS offset Machine code Assembler code Comment |
+-----------------------------------------------------------------------------------------+
|0x8e92 4e92 18 0F JR 4EA3h To be secure jump over our |
| inserted part |
|0x8e94 4e94 FA 04 D1 LD A,(D104h) Load the round counter into the |
| register. |
|0x8e97 4e97 FE 00 CP 00h Compare the round counter to 0 |
|0x8e99 4e99 C0 RET NZ If a round was set, we return! |
|0x8e9a 4e9a CD ED 4E CALL 4eed Show the story screen only once at |
| the beginning |
|0x8e9d 4e9d 3E 01 LD A,01h Load value 01 |
|0x8e9f 4e9f EA 04 D1 LD (D104h),A Set it as round counter |
|0x8ea2 4ea2 C9 RET Return to 0b54 |
+-----------------------------------------------------------------------------------------+

- Part 3 -

Overwrite another hopefully unused NOPs for the story part only for the beginning.

+-----------------------------------------------------------------------------------------+
|ROM offset BUS offset Machine code Assembler code Comment |
+-----------------------------------------------------------------------------------------+
|0x8eeb 4eeb 18 09 JR 4EF6h To be secure jump over our inserted|
| part. I believe this is really |
| necessary since there were no |
| RET (C9h) before this NOP section. |
|0x8eed 4eed 3E 00 LD A,00h Equals our "XOR A" (A = A XOR A = |
| 0) from the original code |
|0x8eef 4eef CD A4 2F CALL 2FA4h Change music (Silence because A=0) |
|0x8ef2 4ef2 CD 16 05 CALL 0516h Show story screen |
|0x8ef5 4ef5 C9 RET Return to 4e9d |
+-----------------------------------------------------------------------------------------+

- Part 4 -

Now change the CRC checksum from c131 to c9de (English ROM) or f530 to fddd (Japanese ROM)
with the hex editor as seen in the table above. If your original ROM has another checksum,
then you have to change it as shown in your emulator tool. If you had the same original
checksum as I had, but another checksum after the changes, then you did probably something
wrong.

== Notes ==

* No absolute jumps into the overwritten NOP areas found; relative jumps were not analyted,
but unlikely.

* I used VisualBoyAdvance and a hex editor to disassemble this game. It was really hard to
work at it. Also, this page helped a lot with the CPU commands:
http://nocash.emubase.de/pandocs.htm#cpuinstructionset .

* Please also visit following URL where I posted some great cheat codes I found out by
looking at the memory map:
http://daniel-marschall.blogspot.com/2009/07/gameshark-cheats-forabsolute.html


Zettai Muteki Raijinou (Japan) - NOINTRO
CRC32: 7D03727D
MD5: E870BCCBC307FB32228FA8E4545EDF35
SHA-1: 6269CA535EEA41F4BCFEF99F512F435DAF06C6E3
SHA-256: 4A48001D0EE193C1E9642DA042A689CBC94E1E0650CA9D9A6568082330E849EF