Complex sentence: Gameplay is simple: the player controls a ship which they can detonate at any time, which causes any enemies within a certain radius to explode, which in turn cause other enemies to explode in a chain reaction.
Split into simpler sentences: Gameplay is simple: the player controls a ship which they can detonate at any time. This causes any enemies within a certain radius to explode, which in turn cause other enemies to explode in a chain reaction.