Complex sentence: This caused Zero to initiate the "Les Enfants Terribles" project which caused Big Boss'defection Zero and plot a coup d'état against him, causing the events of Outer Heaven and Zanzibar Land.
Split into simpler sentences: This caused Zero to initiate the "Les Enfants Terribles" project. This led Big Boss to break away from Zero and plot a coup d'état against him, causing the events of Outer Heaven and Zanzibar Land.