hoho, you just set my first mod, I'm gonna try that if i can get a decent person who knows lua, i can do all the spriting, and i might add the predator to make it similar to the new 2010 AVP game (Aliens, Marines, Predator)

The tyranids wouldn't be so difficult to do if it weren't for those godforsaken tails. All I can think of to make them doable is that they either cannot crouch/crawl, or have their tail posed in a 3D fashion that doesn't interfere with their overall body shape. I'd bank on the former, though.