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Show HN: Black Ops II statically recompiled to native ARM64 macOS

54 points by adrbn 9 hours ago | 17 comments

I grew up with Black Ops 2 and wanted to see if I could make it work on my 2020 MacBook Pro. So I used Claude Opus 5.5 to create a tool that converts your copy of the game (from Steam) to a native ARM64 Mac app, with almost 60fps in all areas. The whole game is statically recompilated ahead-of-time (AOT) and does not use any emulator whatsoever, be it Wine, Crossover or Rosetta. The best thing is the performance, although some heat issues are still to fix. You get to play the whole Campaign, local Multiplayer (with bots) and local Zombies (all DLCs maps; you need to have them in your Steam library obviously) at about 60fps. Split-screen was not in the PC version, but I've been working on it lately; it's coming soon! LAN mode is on the roadmap for later too :)

baalimago 2 hours ago

Stuff like this makes me really happy about AI. The convenience that AAA lacks, or that they intentionally withhold, is now within reach.

rvz 40 minutes ago

Don't be surprised about them moving to cloud gaming even more which they already have with Xbox cloud gaming and in the future, the real game will be hidden and simulated behind a world model.

s_dev 20 minutes ago

Companies have been trying to solve the be able to "show" and "hide" same thing paradox for decades now.

The AI will still recreate a game that it can view and interact with.

risyachka 22 minutes ago

Yup. Not just aaa, all games that can afford to.

Massive chance these recompilations just ruined gaming for everyone.

Like on your own- do whatever.

As soon as you share it - you actually harm players, not help them

cedws 2 hours ago

How does it actually recompile, does it use an existing tool? I can’t imagine the agent combs through every routine and hand translates the assembly.

adrbn 2 hours ago

Yes, it uses two already existing tools for the heavy lifting. Remill lifts the x86 machine code to LLVM IR, and LLVM then compiles that IR to ARM64. And no, nobody translates the assembly by hand luckily, not me nor the agent. All of these 150k functions go through this automatic chain I explained before.

What I wrote with Claude is basically everything else: custom LLVM passes, a hand-written runtime that replaces the Windows calls, a Direct3D 11 to Metal layer and the shader translation! Plus fixing the crashes one by one by iterating and playing. All details are in the Pipeline section of the README if you're interested: https://github.com/adrbn/bo2-mac#pipeline

cedws 55 minutes ago

Thanks.

doodlesdev 39 minutes ago

[dead]

unwind 21 minutes ago

Uh it's a cool project for sure even if its getting hard to keep these apart and seems kind of strange to do all that targeted solely on game ... but cool!

This is very confusing to read, though:

What I wrote with Claude: [...] a hand-written runtime

To me you have to pick one or the other. Claude has no hands.

saagarjha 2 hours ago

> Remill lifts each function to LLVM IR, a chain of our own passes rewrites that IR, and the result is linked with a Win32 runtime written by hand, whose Direct3D 11 is drawn by Metal. There is no Wine and no JIT: the game runs as native code, in one process. About 150,000 functions are translated across the three executables. Only the short sequences that the copy protection hides run in a small x86 interpreter, and so does any code the translation missed, so a hole is built to cost speed rather than crash the game.

phaser 4 hours ago

what was your workflow for creating this? there's now extra guardrails around decompiling / reverse engineering, do you think this is still possible to do or were you just lucky enough to do it before the guardrails?

adrbn 4 hours ago

Well it took me almost 4 months using parallel Claude sessions, each one of them working on its own worktree. I also made a point of measuring before considering anything fixed, and I tested and played throughout the whole development so this way I knew the real impact of every change it was applying. I'm yet to start another similar project to see how things have changed in terms of guardrails, but it has not been a problem for me in the last month AFAIK. Sessions keep working without any problem and Codex (Astra) has also been of a great help in addition, when I did encounter some refusals with Claude. Also maybe (big maybe!) the fact the tool only works from a Steam copy helped, I guess.

addandsubtract 2 hours ago

I would be interested in a write up of how to get started with something like this. I know there are tools like REA now, but it still seems daunting for someone that has never done game development or decompiled anything before.

adrbn 2 hours ago

Check the repo: the README already has a Method, Findings and Pipeline section, so that's kind of the start of a guide already.

If you want something simpler to begin with, look at N64Recomp (that's what gave us the PC ports of Zelda Majora's Mask) or XenonRecomp (Xbox 360, used for Sonic Unleashed), they're static recompilations too and way better documented than mine as of now haha. And to look inside an executable, Ghidra is free (made by the NSA, fun fact). A proper write-up might come at some point, but no promises on a date :)

Also, I had never done anything like this before either!

Benard-dev 3 hours ago

This is great, I also grew up on Black Ops 2. How big is the recompiled binary compared to original?

alanfranz 38 minutes ago

The README is very much AI slop. Why don't you people write by yourself at least your READMEs? Explain the why? Explain the advantages? You can still ask AI for reviews.

Almost every paragraph makes me want to ask: "so what?"

> There is no Wine and no JIT: the game runs as native code, in one process > the campaign runs at 51–60 frames per second

So what?

Is it a matter of running the game in itself? Was the game not running on Apple M-series in any way, so you're unlocking something that was impossible before?

Or does the game just ran faster (more FPS), load quicker, render better, what?

There's no comparison to how the game runs on x86, or how it runs on M-series with translation layers (IF it runs).

This is an exact manifestation of the AI slop problem. A lot of details. A lot of "how". A lot of "what". So little "why" - you need to read a lot and in the end your questions are never answered, and you don't understand if the project makes sense at all or is just something "we did it because we could". I'm perfectly happy to read AI generated text if it's properly and clearly written and answers the right questions.

adrbn 23 minutes ago

The why is in my post actually, BO2 never came out on Mac. On M chips you'd have to go through CrossOver and Rosetta, here it's native ARM64 so I can fix things and add stuff like split-screen, which the PC version never had. Fair point on the CrossOver benchmark, I haven't done it yet. I'll add a why section to the README, thanks.

alanfranz 18 minutes ago

Where did I complain about your post? I complained about the README.

Thanks for adding the Why in your readme, btw :-)

By the way, the why in the README is still unclear:

Your post says:

> see if I could make it work on my 2020 MacBook Pro

This seems to imply that it didn't work on the 2020 MacBook Pro (which I suppose is the M1)

> On Apple Silicon the usual way to play it is Wine or CrossOver on top of Rosetta 2, which translate the game while it runs

This is from the README. So, it was playable on M-series already? Just not natively? Then, what kind of benefits does your translator offer?

> so I can fix things and add stuff like split-screen, which the PC version never had

So THIS is the advantage? I'm not sure why this advantage would be limited to the ARM64 version BTW; cannot you patch the original?

That's the why I'm asking for, and that's where LLMs suck, and where you need to have your human brain & skills actually work.