What it sounds like. Comes with replacement textures for three texturesets. (Some textures are used in more than one set.) Generally an interesting collection...
A huge spiral staircase, with the top ending just above the bottom. Some of every monster... and every weapon. (No explodabobs.) All in a nice space setting...
A whole bunch of platforms that are invisible, except from above... set in space. Really tough to figure out where your enemies are... especially if you play with the motion sensor off. There's a catwalk around the outside for those of you who get queasy.
A couple of large rooms on one side with a jug in 'em, some really stupid bobs that insist on freeing that jug, and a nasty crusher. There are very good reasons for braving the crusher... like the jug.
