The Labyrinth
6 levels (5 plus a network level). Insane numbers of baddies, but generally a pretty nice layout. lots of ammo... and you can start on most levels, because the creator was nice enough to add extra weapons as you go along. If you're playing on a 68K machine, be careful in the big outdoor area in the vacuum level... you might want to use Ignore Zero Divides to avoid a crash from certain views