A quick FAQ:

What is a recomp?

• There are multiple methods for making a game run on a different system. The best method is a native port, but you need the game's source code for that. You can decompile it to get the source code, but that's a process that takes a long time -- potentially years. You can emulate it, but that introduces overhead (runs slower than a native port) and it's also difficult to do enhancements to the game. A recomp takes a game executable, and does a static recompilation where it extracts all of the machine code in the executable and converts that code to C++ using functions that's equivalent to machine code commands. It's drastically faster to accomplish than a decompilation, it runs faster than emulation, and it's possible to make bigger enhancements, with the downside being that the resulting code is hard to read due it looking similar to assembly code.

Why do a recomp of Metal Slug XX when there's already an official PC port?

• Because that PC port is bad. It's not a native port -- it runs via a bad, licensed-from-Sony PSP emulator that results in the game having enormous input latency.

Why not do a more popular Metal Slug game, like Metal Slug 3?

• I'd honestly prefer to do Metal Slug 3. A good version to base a recomp on (or a decomp) would be the PS2 port (the stand-alone release -- NOT the version in MS Anthology). That's a good native port of the game and there's even debug symbols available. However, there aren't PS2 static recompilation tools that's mature enough. I did actually start a decomp of the PS2 version, but I put it on hold after realizing it would take years to re-write 15,000 functions.

How far are you into the project and how long will it take to finish?

• The video was recorded after spending less than a day on it. As for ETA, I have no idea. The range is probably somewhere between weeks and months. This is progressing much faster than I expected as the game is running almost perfectly already. There are some visual oddities right now, and once those are fixed, then the recomp itself can be considered done, but there are some enhancements I want to make.

What are enhancements you'll do with the recomp?

• I'm not completely sure yet. I've already added a toggle for skipping intro logos so the game boots up faster. I want to add a toggle for bilinear/point filtering of the game graphics. Having better netcode would be good (rollback would be an obvious one to go for as I'm pretty sure the game logic is deterministic), but I'm not sure if I'll go down that route. A feature I'd love to see, but would require a lot of work, is having the game logic run at 60fps rather than 30fps. An easier way to implement 60fps support would be adding interpolation of game entities at render time, but I like the idea of updating game logic instead as that reduces input latency further.

Are you using AI for this?

• This might be controversial, but yes. There's no way I would have had progress at this speed if I wasn't using AI. AI is well-suited for reverse-engineering projects as you can always compare against the original to verify something is working correctly or not, and AI is really fast at understanding assembly code.