Open Tournament is a first-person shooter game built on Unreal Engine, inspired by classic arena shooters like Unreal Tournament and Quake. The game implements comprehensive systems for player movement, combat, AI, user interface, audio, and networking. It features a modular architecture using Unreal Engine's plugin system, with extensive use of the Gameplay Ability System (GAS), Enhanced Input, and replication for multiplayer functionality. The codebase shows thoughtful architectural design in several reusable systems, particularly in settings management, UI composition, messaging, and loading screen handling.
The Doomsday Engine is a modular game engine and source port for classic FPS games (Doom, Heretic, Hexen, Doom64) with client-server architecture. It provides enhanced rendering (OpenGL), audio systems, GUI frameworks, networking, and scripting capabilities. The engine supports extensibility via plugins and includes tools like Amethyst for documentation processing. The codebase shows strong separation of concerns with distinct libraries for core functionality, game logic, rendering, and UI. While actively maintained, it exhibits technical drift due to platform-specific conditionals, legacy code sections, and complex dependency management.