The Sims 3
The Sims 3 (PC, 2009) has code that decompiles almost back to source.
Data checked 2026-10-12 · unbaked registry
Projects
Sims 3 script mods (gameplay in .NET/Mono C# assemblies)
Readable bytecodeNative engine + Mono C# gameplay DLLs (Sims3GameplaySystems.dll)
What you need
You need your own copy of the game: these projects ship code only.
More on PC
GameMethodYearStarsLast push
PCMindustrySource releaseAgent environment201929k2026-10-11PCosu!Source releaseReadable bytecode+1200719k2026-10-12PCCommand & Conquer Remastered CollectionSource release202021k2025-01-16PCRollerCoaster Tycoon 2ReimplementationAgent environment200216k2026-10-12PCDune 2000Reimplementation199818k2026-10-11PCAge of Empires IIReimplementation199914k2026-10-03PCCataclysm: Dark Days AheadSource release201313k2026-10-12PCCivilization VSource releaseReimplementation201011k2026-10-12Found via store.steampowered.com/app/47890/
GitHub data checked 2026-10-12. Notes are summaries from the research pass; the project pages are the authority.