In the far reaches of space, factions of humanity battle over a rare and dangerous resource known as Rift Energy. Colonies of humans called Rifters have been exploring the "Frontier" of planets, but find their way of life threatened by the Outcast, a ruthless species of humans who have mutated into psychotic monsters due to exposure to this very same Rift Energy. Caught in the middle is Emmett Graves, a hired gunslinger ostracized from society because of his own exposure to Rift Energy, leaving him partially mutated, but still able to retain his humanity. Graves is drawn back to his home settlement to face a mysterious outlaw and his war band of Outcast warriors.
Starhawk provides fast paced third-person shooter action set in this lawless frontier of space, allowing players to instantly alter the battlefield by calling down offensive and defensive structures in real-time from an orbiting drop ship, all while blasting away at enemies in the middle of huge single-player or multi-player firefights. [From IGN]
It's currently in the beta stage 1.3 and includes vehicles such as Jet Bikes (very much like in Star wars) Jeeps, Tanks and StarHawks, transformer like massive machines which transform from bi-pedal Robots to agile flying jet planes in seconds!
You get a small stream of Rift energy (the games only resource) when you are in your base area, and once you leave the area it can only be collected by blowing up regularly spawning barrels of it or killing the enemy and taking what energy they had collected, this is all done automatically (think sonic when you got the magnetism power up)
The energy is then used to build vehicles which use small amounts of evergy, or increasing in size important structures and energy use, such as a basic wall which will cost 1 unit of energy, to a kinetic barrier (big sci-fi energy shield thing) which will cost you 9 units.
There is a single player campaign but this is under wraps until the release, but in all honesty I am buying this day 1 simply for the awesome multiplayer, 32 people online and it is seamless, no rubber-banding or skips at all in the 3 weeks I have been playing it!
You still have time to download and play the beta, which I HIGHLY recommend you do, you will not be disappoint