A rambling level, with several areas all opening on a small arena. Secret (or almost secret) areas offset by the danger/ damage needed to get to them.

This is really set up as a coop level, shoot everything that moves level, but you can play it alone, if you like. Sort of a plot, but mostly, it's just run-around-and-kill-everything.

A huge, mostly symmetrical level based around a central open area. (I'd hesitate to call it an arena, since it's full of holes dropping into the sewers below...) Level design is quite attractive, with lots of care shown to details.

Jeff Swartz is definitely a mapmaker to watch. This is a big level, but moving around is just beautiful.