Much more slick than 3D-SFCave, but similar in principle, is the helicopter game: http://www.seethru.co.uk/zine/south_coast/helicopter_game.htm

Nice one.

Excellent! I remember playing the original SFCave (http://www.sunflat.net/ja/games/sfcave.php) for hours on end a few years ago. That 3D version is at least twice as difficult (but still just as addictive)!