Complex sentence: The game uses a game engine based on the Stratagus engine, originally the game data structure was separated fromt the graphical engine, but it was merged into the gsme in 2007and the Stratagus project was merged into the Bos Wars project shortly after the engine change.
Split into simpler sentences: The game uses a game engine based on the Stratagus engine. Originally the game data structure was separated from the graphical engine, but it was merged into the game in 2007, and the Stratagus project was merged into the Bos Wars project shortly after the engine change.