I played this game while ago and wondered if anyone happened to know the name. The premise is that you are a robot, and you run around a farm shooting vegetables with a distinctly Goodbye Galaxy-like raygun. Every so often you come across a farmer who you must save from the vegetables. When you kill a vegetable if dissolves into little glowing bits which can be collected for ammo, health of points. I played it on a G4 iMac at my church a few years ago. I got through level one, and saw the beginning of the second level, which featured a cave full of brightly-coloured crystals. Oh, and it's a (very arcade-y) third-person shooter.