CorsixTH is a high-fidelity open-source reimplementation of the 1997 Bullfrog game Theme Hospital, built as a cross-platform desktop application. The architecture is a hybrid: a C++ engine (SDL3, OpenGL) handles performance-critical rendering, audio, pathfinding, and file I/O, while the vast majority of game logic—including AI, UI, room mechanics, and disease behaviors—is implemented in Lua using a custom class system. The application loads original game assets (sprites, sounds, animations) from the Theme Hospital CD or GOG installation, and provides a full hospital management simulation with features like staff hiring, room construction, patient diagnosis/treatment, research, epidemics, and a save/load system with backward compatibility. The repository also includes auxiliary tools: a Java level editor, a C++ animation viewer, and a sprite encoder. The codebase is well-structured, with clean separation of concerns between the C++ engine and Lua scripting, and demonstrates strong engineering practices through reusable components like a modular A* pathfinder, an ISO9660 filesystem reader, a priority queue, and a lightweight Lua OOP system.