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 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, 

Minimal requirements: 
 

Processor: Quad Core Processor

Graphics: Shader 3.0 / OpenGL 3.2 +, 1 GB GPU RAM

Memory: 8 GB RAM

Disk space: 5 GB available space

System: Windows 7 64 bit