UE4SS-RE/RE-UE4SS

RE-UE4SS is an injectable Lua scripting system and modding platform for Unreal Engine 4 and 5 games that provides runtime access to the engine's object system alongside code generation and debugging utilities.

The tool solves the problem of creating mods for UE4/5 games without modifying game files or rebuilding the engine. It works by injecting into the running game process and exposing the Unreal object system through multiple interfaces: a Lua scripting API for writing mods in Lua, a C++ modding API for native code mods, and a blueprint mod loader that spawns blueprint-based mods automatically. The system also includes utilities for reverse engineering, such as SDK generators that produce C++ headers compatible with Unreal Header Tool, a live property viewer and editor for inspecting and modifying object state at runtime, and dumpers that extract mapping files and actor data from loaded games.

Adoption suits developers who want to create mods for specific UE4/5 games without access to source code or who need to understand game internals through runtime inspection. The tool targets games running UE versions from 4.7 through 5.8, though the README notes it is not a plug-and-play solution that works universally across all games—users may need to update address-of-byte patterns themselves. Installation is straightforward, extracting files to the game's Win64 binaries directory, with support for custom game configurations and environment variables to specify additional mod directories. The tool supports command-line options to disable UE4SS temporarily or specify custom build paths for testing.

Development shows active maintenance with regular updates addressing compatibility across engine versions. The project maintains comprehensive documentation covering both user installation and mod development workflows. The codebase is written in C++ and includes tooling for multiple dumping and generation tasks, indicating ongoing refinement of the reverse engineering capabilities.