A beta version of the Galactic Control 15mm sci-fi rules is available for download.
From their announcement:
Galactic Control, the 15mm scale science fiction tabletop wargame has been released for play testing. Interested parties can download the ruleset.
Feedback is welcome and can be done on the official forums. Feedback on the ruleset will help towards making the game more balanced and fun as well as easier to understand.
Work has started on faction army books and a quick reference sheet.