I'd love it if there was some way to contribute to ongoing game decompilation projects, with a similarly streamlined web interface - it's something I'd be willing to dedicate some brain time to every so often, but setting up the toolchain etc. feels too much like work.
By the way, I was able to "cheat" on the second lesson with
That's what decomp.me is for, when I'm stuck on a function in my own projects I usually set it up on there and link it in the codebase so anyone can pick it up. Sometimes I like to browse the front page and hope I know enough to silently match somebody else's function (usually stays as a hope though...)
decomp.me is also a great tool! The playground section of the site allows you to turn the code into a decomp.me scratch.
I also use the objdiff wasm on the frontend for the assembly diffing. I don't see much point in reinventing the wheel and these tools are already great, so I'll deffo be leaning on them when I can
I was thinking of something similar as well, perhaps a section of this site after you've completed the course where we show functions from popular decomp projects that aren't 100% matched, and you can match it. Doing so will magic up a PR or something.. It's a great idea!
As for cheating, the community calls this a fake match. I don't check that the code you submit conforms to what I expect, I only check if the assembly matches. You can do interesting things where you do a series of bit shifts and bit masks, and you can replicate an equality operator `a == b` or a low clamp `x < 0 ? 0 : x`. I'm not sure if I'll lock this down or not, for people who have accounts, I can see their submissions so I think I'll play it by ear and see what happens. If it looks like people are constantly fake matching, I can look at tweaking the lessons or locking it down more
Dumb question about reverse engineering binaries: is there a way to only do it piecemeal? I'm eventually waiting for LLMs and harnesses to get good enough to reverse engineer BFME (old Lord of the Rings game that still has an active modding community), but it's a multi GB sized game that would have to be done in bite-sized pieces.
Basically; can you reverse engineer in bite sized pieces, and recompile/customize their behavior, without needing to do it all at once?
Most decomp projects (that I know of) are Ship of Theseus style projects where the minimum unit is a function, give or take alignment requirements and quirks of the compiler. I’m the MIPS side, tools like Splat and SPIM can help identify function and even source file boundaries, generate inline ASM C files[0], and write linker scripts to build a matching binary. You can then go through and replace the ASM functions one at a time until you just have C left.
Damn this is next level. Congratulations on your achievements!
When Fable was around I thought i'd test it by taking an old piece of Windows software from the late 90s/2000s(ModPlug Player) and seeing how well it could convert it to being a native Mac application.
I was blown away at how it got 85% of the way there in one prompt. Things such as writing a PE extractor, recovering the complete skin, menu tree, full accelerator table, all dialogs, and then it delved into the registry value names as well. Some more prompts got it to 99%(I was happy with that and stopped)
I then took an old 1999 DOS demoscene and yet again it did wonderful magic and got me a native mac build.
I dropped everything I was doing and just started going through all these old apps that I couldn't easily enjoy since im on a Mac. It got to the point where I was losing sleep over it(was just so excited).
The fun ended when I was stopped mid-project with the Fable ban. Opus just does not compare and essentially killed all the enthusiasm after the nth failure of it to complete the task.
It made me realize that among the efforts of the RE community, and the emerging capabilities of these frontier models, in the future we could have the possibility living in a renaissance of open computing if we want any software we see on the market to be forever remixed and tailored to our uses and completely open.
I don't know how the business and legal side will deal with this. There needs to be new frameworks and ways of thinking about this stuff.
I'm just happy that hopefully no code will ever be lost to the sands of time ever again.
AI is being used in many retro game decomp projects!
One of the reasons I went down the path of learning decomp myself was because AI had hit a wall. Matching decomp is quite a bit harder than just normal decomp as even simple things like using an if/else instead of a terney actually change the assembly. AI did an amazing job of getting to 95% matches on nearly all functions, but once it got to that tail end, it started to struggle quite a lot and would often just claim "it's impossible". So that's when I pivoted and started learning actual decomp myself so that I could prompt AI better and finish off the star fox adventures decomp!
I say this every time it comes up, but polluting a decomp project with AI generated code is risky, imho. What makes decomp legal (in the US) is that it’s a creative transformation performed by a human and the resulting copyright of the code that just happens to compile to the same binary is owned by the person doing the decompiling.
USPTO and court precedent is leaning heavily toward LLM output not being transformative on its own, making it mechanical, and no longer fair use and in violation of copyright. This puts a legal gray cloud on a project where most contributors couldn’t defend themselves if a rights holder goes after it, and there’s a high likelihood that they would succeed. On the other hand there’s enough case law protecting human decompilation that even the most litigious game companies don’t go after decomp projects that have historically been done by humans.
(I’m not a lawyer, I’m not your lawyer, this is not legal advice, etc., etc.)
Before the advent of LLMs, ML was used in upscaling the assets and pre-rendered backgrounds of the first 3 classic Resident Evil games: https://www.reshdp.com
Makes one wonder, why should anyone embark on learning this intricate and time-consuming art of reverse engineering when LLMs are on their way to automate it in seconds...
The backend is closed source, but it runs all on AWS Lambda/DynamoDB/APIGateway and is written in Rust. Getting the compiler running in a Lambda was an adventure of it's own
I’d be interested in hearing more detail on that. I’m actually surprised you were able to get the compiler, I assumed it would be expensive and proprietary.
Are you on mobile? You'll need to switch to the code/review tab to see. I think mobile support is a bit funky, I'll look at fixing that as soon as I can!
I'd love it if there was some way to contribute to ongoing game decompilation projects, with a similarly streamlined web interface - it's something I'd be willing to dedicate some brain time to every so often, but setting up the toolchain etc. feels too much like work.
By the way, I was able to "cheat" on the second lesson with
I gave up at https://decomp-academy.dev/lesson/workflow-what-matching-mea... when I was presented with a wall of LLM-flavoured textThat's what decomp.me is for, when I'm stuck on a function in my own projects I usually set it up on there and link it in the codebase so anyone can pick it up. Sometimes I like to browse the front page and hope I know enough to silently match somebody else's function (usually stays as a hope though...)
decomp.me is also a great tool! The playground section of the site allows you to turn the code into a decomp.me scratch. I also use the objdiff wasm on the frontend for the assembly diffing. I don't see much point in reinventing the wheel and these tools are already great, so I'll deffo be leaning on them when I can
I was thinking of something similar as well, perhaps a section of this site after you've completed the course where we show functions from popular decomp projects that aren't 100% matched, and you can match it. Doing so will magic up a PR or something.. It's a great idea!
As for cheating, the community calls this a fake match. I don't check that the code you submit conforms to what I expect, I only check if the assembly matches. You can do interesting things where you do a series of bit shifts and bit masks, and you can replicate an equality operator `a == b` or a low clamp `x < 0 ? 0 : x`. I'm not sure if I'll lock this down or not, for people who have accounts, I can see their submissions so I think I'll play it by ear and see what happens. If it looks like people are constantly fake matching, I can look at tweaking the lessons or locking it down more
Dumb question about reverse engineering binaries: is there a way to only do it piecemeal? I'm eventually waiting for LLMs and harnesses to get good enough to reverse engineer BFME (old Lord of the Rings game that still has an active modding community), but it's a multi GB sized game that would have to be done in bite-sized pieces.
Basically; can you reverse engineer in bite sized pieces, and recompile/customize their behavior, without needing to do it all at once?
Most decomp projects (that I know of) are Ship of Theseus style projects where the minimum unit is a function, give or take alignment requirements and quirks of the compiler. I’m the MIPS side, tools like Splat and SPIM can help identify function and even source file boundaries, generate inline ASM C files[0], and write linker scripts to build a matching binary. You can then go through and replace the ASM functions one at a time until you just have C left.
0 - for example: https://github.com/Xeeynamo/sotn-decomp/blob/master/src/boss...
Damn this is next level. Congratulations on your achievements!
When Fable was around I thought i'd test it by taking an old piece of Windows software from the late 90s/2000s(ModPlug Player) and seeing how well it could convert it to being a native Mac application.
I was blown away at how it got 85% of the way there in one prompt. Things such as writing a PE extractor, recovering the complete skin, menu tree, full accelerator table, all dialogs, and then it delved into the registry value names as well. Some more prompts got it to 99%(I was happy with that and stopped)
I then took an old 1999 DOS demoscene and yet again it did wonderful magic and got me a native mac build.
I dropped everything I was doing and just started going through all these old apps that I couldn't easily enjoy since im on a Mac. It got to the point where I was losing sleep over it(was just so excited).
The fun ended when I was stopped mid-project with the Fable ban. Opus just does not compare and essentially killed all the enthusiasm after the nth failure of it to complete the task.
It made me realize that among the efforts of the RE community, and the emerging capabilities of these frontier models, in the future we could have the possibility living in a renaissance of open computing if we want any software we see on the market to be forever remixed and tailored to our uses and completely open.
I don't know how the business and legal side will deal with this. There needs to be new frameworks and ways of thinking about this stuff.
I'm just happy that hopefully no code will ever be lost to the sands of time ever again.
AI is being used in many retro game decomp projects!
One of the reasons I went down the path of learning decomp myself was because AI had hit a wall. Matching decomp is quite a bit harder than just normal decomp as even simple things like using an if/else instead of a terney actually change the assembly. AI did an amazing job of getting to 95% matches on nearly all functions, but once it got to that tail end, it started to struggle quite a lot and would often just claim "it's impossible". So that's when I pivoted and started learning actual decomp myself so that I could prompt AI better and finish off the star fox adventures decomp!
I say this every time it comes up, but polluting a decomp project with AI generated code is risky, imho. What makes decomp legal (in the US) is that it’s a creative transformation performed by a human and the resulting copyright of the code that just happens to compile to the same binary is owned by the person doing the decompiling.
USPTO and court precedent is leaning heavily toward LLM output not being transformative on its own, making it mechanical, and no longer fair use and in violation of copyright. This puts a legal gray cloud on a project where most contributors couldn’t defend themselves if a rights holder goes after it, and there’s a high likelihood that they would succeed. On the other hand there’s enough case law protecting human decompilation that even the most litigious game companies don’t go after decomp projects that have historically been done by humans.
(I’m not a lawyer, I’m not your lawyer, this is not legal advice, etc., etc.)
Before the advent of LLMs, ML was used in upscaling the assets and pre-rendered backgrounds of the first 3 classic Resident Evil games: https://www.reshdp.com
Makes one wonder, why should anyone embark on learning this intricate and time-consuming art of reverse engineering when LLMs are on their way to automate it in seconds...
You can tell this basically about anything software related these days. Yet when human is in the loop, the insight is still needed.
The backend is closed source, but it runs all on AWS Lambda/DynamoDB/APIGateway and is written in Rust. Getting the compiler running in a Lambda was an adventure of it's own
I’d be interested in hearing more detail on that. I’m actually surprised you were able to get the compiler, I assumed it would be expensive and proprietary.
This is cool as hell.
On the first lesson, it tells me there's a target on "the right". There isn't anything to the right, I've in clue where to look.
Are you on mobile? You'll need to switch to the code/review tab to see. I think mobile support is a bit funky, I'll look at fixing that as soon as I can!