Or course, your map should also look good while I'm dodging and jumping and crouching and strafing.
I've seen plenty of castles, fortresses, dungeons, warehouses, factories and processing plants.
As long as they don't crush my framerate, make 'em as pretty as you like.
It would also be nice if the areas/effects created somehow added to gameplay.
I'd rather play something my computer can run than keep having my hardware become that much more useless 4 times a year (every season that new games come out). I think that explains part of the open-source engine freeware standalone allure. I don't care if it looks like Q1/2/3, if it's fun to play, and offers me something those games or their mods didn't. Or that I can't get just anywhere for free. Witness Tremulous. You can't kill the metal...