Get Hellgate: London, I think it's pretty cheap these days. Of course it's repetitive but isn't that exactly what you just described? Or if you prefer something shorter get the Alien Shooter games.
From the tiny bit I've seen of HellGate London, I'm a little turned off by the FPS/TPS aspects. But Alien Shooter looks like some sort of awesome! Lucky me I don't judge a game by it's outdated isometric graphics! &P
But seriously, I'm sad that these games are not available for wonderfully relaxing couch-gaming, and that there's no local multiplayer. A big part of the appeal of Gauntlet, and Alien Syndrome, was playing local multiplayer with my brother or others. Gauntlet Legends on the 64 was great, I could even play that game with all my little cousins.