Earlier this month I made a blog post called How I learned to play The Incident and other GTROM favorites... chronicling my efforts to create patches to get various GTROM based homebrew games to run on alternate mappers. This is potentially useful since GTROM support in emulators is thin even today so using a more common mapper allows play in places where it otherwise wouldn't be possible. I think it's an interesting read since this isn't something I knew about coming into the project.

In response to my post, Kevin graciously approved my releasing the patches for his games and so I just wanted to let everyone know they are available on my Neocities homepage if you are interested.

https://bacteriamage.neocities.org/gtrom/index.html

• KHAN Games 4-in-1 Retro Gamepak
• Scramble
• The Incident

These are just the patches and their source code. You'll still need to obtain a ROM dump from your cartridge so you have something to patch. I've included my original dump script though in case you have access to a Kazzo.

As aside and separate plug, the Game Genie codes I posted for The Incident a while back work on both the MMC1 and GTROM versions of the game. In fact, I actually created them using the patched version.

Cheers!


 

Dled and was curious about the GG stuff. How do you start with finding those codes? I scrolled through real quick just now before work, but where does one start with learning how to manipulate with the GG? Did the codebooks have a tutorial to get you started? I haven't tinkered with that thing since the NES and making Mario moonwalk.

Congrats on releasing these, and thanks so much for all the time and attention you gave to the things I made!

Thanks! It's been great fun playing them as well as pulling them apart! 

I do all my cheat code creation work in FCEUX. I just use the debugger and the other reverse engineering tools it provides to find the program code that I'm looking for. Then once I know the ROM address FCEUX also has Game Genie code creation tool built-in. You give it the ROM address, the value you expect to find at that address, and what value you want to change it to and that's all it takes. A 6502 Reference is helpful is knowing the byte values for the various instruction opcodes.

I've been programming a long time but I only started trying reverse engineer things more recently in 2010 or so when I first started trying to reverse engineer the password systems for various games. Really just takes practice. The first time I tried to do it took many hours to find the code I was looking for. Now I can usually find most stuff in a few minutes. Firmly undertanding the console and the toolset you're using helps alot too. Once you've found the code changing it realy isn't any different from any other programming.

 

Excellent! As soon as I can purchase ROMs of these games, I'll now have a way to play them on NesterJ for PSP! Thank you so much!

Any plans for making a patch for the upcoming Nescape...?