Open-IG is a Java-based space strategy game (Open Imperium Galactica) where players manage colonies, build fleets, engage in space/ground combat, conduct research, and handle diplomacy. The game features a layered architecture with distinct model, mechanics, screen, UI, and render components, supporting six languages and multiple campaign/skirmish modes. Game state flows from model objects through mechanics systems to screen/UI components for display, with save/load functionality persisting state. The build system uses Gradle, and the game includes its own JOrbis/JOGG libraries for Ogg Vorbis audio handling. The codebase demonstrates solid engineering practices with clear separation of concerns: model (game entities/data), mechanics (AI/planning), screen (UI management), UI (custom components), and render (drawing). Notable reusable systems include a natural string sorter, LRU cache, undo/redo framework, data filtering component, and text renderer. Recent activity (2026 commits and updates) indicates active maintenance, while the modern Gradle build system and lack of obvious deprecated APIs suggest low technical drift.