Planetary Annihilation: TITANS is now available on Steam, offering a standalone expansion to Uber Entertainment's space-based real-time strategy game for Windows, Linux, and OS X (thanks Ken). As noted in this forum post, this is free for all Kickstarter backers and for all who signed up for the Mystery Mayhem tournament before August 18th, and a 66% discount is provided to those who bought the original Planetary Annihilation before the launch of TITANS. Here's a launch trailer and here's more on the release:

TITANS is the huge stand-alone expansion to the already massive-scale RTS Planetary Annihilation, which includes the base game and adds tons of new features:

Devastate your enemies with 5 massive Titan-class super units like the like the earth-shaking Atlas bot and lightning-wielding Zeus airship!

Expand your strategic arsenal with 16 new units such as versatile Hover Tanks, indomitable Orbital Battleships, and voracious Nanobot Swarms!

Elevate your game with new planets that feature multi-level terrain available in both single and multiplayer. Get up to speed faster with a new, streamlined tutorial experience, then take your game to the next level with the new Bounty Mode option for AI skirmish and multiplayer,