Some good folks have been hard at working at turning back the clock on the Natural Selection universe and converting it to a 2D format, know as Starstrike. Right now the AI is fairly simple, but their latest blog update talks about how the marine AI is quite competent, but work is needed for the alien AI still. Make sure you read the site for any problems you may have and give them some feedback. Personally, I suck in 2D just as much as I did in 3D.