Well, the upcoming rules by Spacejacker, Gunstorm, should be perfect on a 2x2 table, and of course Tomorrow's War was designed specifically to be played on such an area.
Spacejacker has posted the basic rules for free on his website and they look magnificent -- I'm very excited by the simple mechanics and the subtle challenges facing the player due to the random turn sequence. He's done an excellent job.
http://tinysolitarysoldiers.blogspot.com/2013/04/gunstrorm-beta-is-ready.html