InstantAction has announced the debut of their open beta for Mac OS X users. Gamers can register on the site and play Rokkitball, Marble Blast Online, Think Tanks and the FPS, Fallen Empire: Legions. Mac owners can also play PC users with cross platform compatibility. System requirements are Mac OS X 10.4.11 (or later) with Intel chipsets for some of the games, while others need Mac OS X v10.5.4. Safari 3 and Firefox 2 are supported. Check with the site for more specifics.