An almost excessively accurate space sim. This game is not for the faint of heart, but if you like space and physics and don't mind getting your hands dirty with some math now and again, I cannot recommend this game enough. Build ships using modules you've made that run on simulated physics and chemistry, then take them into combat against other ships in full-scale space combat. No other game will give you any idea what combat might actually look like in space. This one will.