Fan Project Decompiles Nearly All of Super Smash Bros. N64 Code

The engineering decisions Masahiro Sakurai's team at HAL Laboratory sealed inside a 1999 N64 cartridge are now almost entirely readable. A volunteer project called ssb-decomp-re, led under the GitHub handle VetriTheRetri, has reverse-engineered 95.75% of Super Smash Bros. for Nintendo 64, converting the game's compiled machine code back into human-readable C until the output matches the original cartridge byte-for-byte.

At that coverage level, nearly the entire game's logic is legible: physics, input handling, AI behavior, hitbox calculations, and crowd reaction systems. What that legibility reveals is instructive for anyone who builds games today.

The decompiled damage code exposes the exact implementation of the "Sakurai angle," a mechanic named after the game's director that assigns knockback angle 361 a special dynamic behavior. Low-force hits send opponents sideways; high-force hits launch them diagonally upward. The game selects between trajectories in real time based on whether the target is grounded or airborne, using a linear interpolation scaled by knockback magnitude. Competitive players have understood the effect empirically for years. The decompiled code names the constants directly, including the threshold values that govern the transition.

The code also documents a detail that no amount of frame-data analysis could surface: when a knockback angle falls between 75 and 115 degrees, the crowd audio system is 20 percent less likely to trigger a gasp reaction. That is a deliberate design decision, buried in a binary for 27 years, now a commented line of C.

For developers who work on the Smash franchise today, that kind of legibility has concrete value. Sakurai's original engineering choices, made on constrained N64 hardware with a small HAL team, have influenced every sequel in the series. Seeing those choices in source code clarifies which behaviors were intentional mechanics and which were artifacts of hardware constraint, information that matters when deciding what to preserve and what to revise.

The project does not distribute a ROM and cannot be run without a legally-owned copy of the original cartridge. The distinction has proven meaningful elsewhere: completed decompilations of Super Mario 64 and The Legend of Zelda: Ocarina of Time have produced native PC ports and accessible mod tooling without operating as piracy vectors.

A separate effort, Smash64Recomp, has already produced a playable Windows and Linux port of the game using static recompilation, a technique that bypasses the need for a full decompile. That project's developers credited the decomp team's reverse-engineering work as foundational to their own modifications, noting that headers and functions from VetriTheRetri's project were used directly.

At 95.75%, the remaining 4.25% is the difference between a research artifact and a complete, buildable document. When the final functions match, the full engineering of the game that invented modern platform fighting becomes source code: something developers, archivists, and modders can read, adapt, and build from, on hardware Sakurai's team never imagined writing for.