Quote from CampaignjunkieMy own little idea: make something that doesn't look like it came from the engine it uses. On GoW, don't make some muddied blue-grey-brown mansion. On Source, don't make a wrecked city lit in fluorescent yellow and teal. On FarCry, don't make a jungle island... etc. For that (optional) extra paradoxical kick (and to level the playing field) - stock assets only. Bonus points if it looks like an actual map and not just some diorama you threw together.
I love this idea. It's pretty easy to do in Source, though, I think, since there's also wilderness beaches and cliffs, sci-fi alien buildings, horror villages filled with zombies, mines, etc.