PoZoUSEMS

Universal Source Engine modding — from the engine interfaces up.

PoZoUSEMS is a from-scratch, universal modding system for Source 1 engine games. First target: Portal 1 (32-bit Source 2007). No Metamod, no SourceMod — everything is built by reverse-engineering the shipped binaries and driving the engine’s own interface system.

Write mods in Luau

Sandboxed Luau runtime per mod. Register console commands and cvars, subscribe to engine hooks — the engine dispatches straight into your script.

DIY reverse engineering

Every offset in the system was discovered by disassembling the shipped game binaries — interface registries, vtables, hook points. No SDK headers required.

Per-game capability caps

All game-specific offsets live in usems-cap, fingerprint-verified at injection time. Unknown builds degrade gracefully instead of crashing.

More languages coming

The mod API is language-agnostic by design: C#, C/C++, Rust, Python, GML and raw ASM bridges are on the roadmap, all sharing one core API.

Current status

Capability	Status
x86 injection (launch + attach)	done, verified in Portal 1
Interface resolution (`VEngineCvar004`)	done, verified
Console commands + cvars from mods	done, verified
Luau runtime (sandboxed, per-mod)	done, verified
Frame hook (`HudUpdate` → Luau)	done, verified
Interface registry enumeration (151 found)	done, verified
Tick hook, entity access, rendering	roadmap (Phase 7 continues)
Launcher (egui)	roadmap (Phase 5)