PlayStation 2 Games Statically Recompiled to WebAssembly for Browser Play

WebAssembly Recompilation for PS2 Games

PlayStation 2 games can now run in web browsers through a static recompilation process, bypassing traditional emulation. This method translates the PS2's Emotion Engine machine code directly into C++, which is then compiled into WebAssembly. The recompiled code integrates with a reimplementation of the PS2's operating system and hardware, utilizing WebGPU for graphics rendering.

Technical Approach and Game Performance

The recompilation process, similar to psp-web-recomp, involves `eerecomp` reading game executables and emitting C++ code that preserves the R5900's specific architectural quirks, such as 128-bit registers and unique floating-point behavior. The first title demonstrated, Gran Turismo 4, a demanding game, runs at full speed (50 FPS PAL) at twice the PS2's resolution in Chrome on integrated GPUs. God of War II also runs, achieving 60 FPS in combat at native PS2 resolution, and 48-60 FPS at twice the resolution.

Operating System and Hardware Reimplementation

The system includes a small PS2 kernel that provides high-level emulation for operating system components like threads, semaphores, interrupt handlers for DMA and vertical blank, alarms, and the SIF channel. This allows the recompiled games to interact with a virtualized PS2 environment. Users must provide their own game disc images, which the repository's scripts convert into a web page.

Bug Discovery and Compatibility

During the porting of God of War II, two bugs were identified that Gran Turismo 4 had not triggered: one in the recompiler and another in the vector unit timing. Additionally, some missing components of the PS2's input/output processor were discovered. These findings indicate the robustness of the recompilation method in uncovering system-level discrepancies.