This is a well-designed game. The gameplay is simple but not simplistic - you must control either a buggy or a flying saucer through 40 levels of dangerous obstacle courses and nasty aliens, destroying various things and reaching the exit. The graphics are decent for a freeware game - they work, which is the main thing - and the gameplay is just varied enough - new elements of the game are revealed as you progress through the levels. The music and sound effects are nothing to write home about, but Caves has it where it counts: it is fun to play. Not too challenging, and the password system will make you come back for just one more go.