I remember back in the day making rudimentary maps with DEU for my mates to play co-op and deathmatch games in. Years ago I attempted to relive those days in Half-Life and Half-Life 2 using Hammer. Sadly, my success was limited; I think the addition of a real third dimension screwed with my brain.
I know I could have spent a lot more time playing and a lot less building if I'd had a tool like Oblige. It randomly generates maps for a variety of games based on the Wolf 3D/Doom engine. These include Heretic and Hexen, among others.
Wait, weren't these games made in *gasp* the 1990s? Yes, they were, but I don't see anything wrong with a bit of nostalgia every now and then.
As far as settings go, you can input a seed (for the random number generator), the game type, and values for monsters, health and weapons. You can even select between single-player, co-op and deathmatch modes. Doom 2 is the best supported, with Wolfenstein 3D being the worst. Doom, Heretic and Hexen are decent.
If you can scrounge up a copy of one of these games, I suggest you give Oblige a whirl. You might be surprised by the results.