CTF? OK. between this and the axe, at one point you basically have to do voxelquake, just so that we can play with that engine :)
that might not be a bad idea for a 'simple enough' game, a fps within everything is destructible. four a side, some simple enough goal, a timer set to 20 minutes and you have a potentially very fun game.
/edit: in an 'afps' level design would make draw distance less of an issue aswell.