Yesterday Assault Publishing has released a demo of their sci-fi rules PMC 2640. "Hell on Echidna" contains all the basic rules, some new background on planet Echidna, a terrain generator for radioactive wastelands, a new scenario, and a selection of units with 2 new ones.
The rules themselves are really worth checking - they allow for smooth, fast company-scale battles.
Link:
http://assaultpublishing.com/?p=1366