played SPAZ during the free weekend and it's actually pretty good, esp cuz you can pick it up for $2 right now ;-) It's a lot like EV:Nova (which I really loved) so I thought you'd like it. Not quite as good as EV:Nova, but it's definitely worth $2.

Have you played Minerva? Supposed to be a fan-made half-life game. Looks like it might be good... and it's free ;-)