The rts behavior works fairly well with the 3d object with a few dummy objects paired up, so an rts is definitely doable.
I'm kind of thinking about perhaps using Scidave's online plug to do a 1 vs 1, or maybe even a turn based chess/checkers with tanks thingy.
One thought I've had is a simulation phase where you build up resources, and invest them into your team. Then have an online part where you do the turn based battle.
Collision detection is pretty much a no go since its 3d, and the online plug really wasn't designed to handle a bullet hell. So I'm definitely leaning more towards the turn based scenario. I'm not sure exactly how to handle that, but chances are it would probably be based on a percentage system, IE chance to hit, chance to do so much damage, etc.
Any thoughts or ideas?
Edit: der forgot the link... may upload screens later.
Link to demo