These past years indie groups seem to be the ones keeping PC gaming alive. After the brilliant World of Goo and the innovative iFluid and Crayon Physics, Defense Grid: The Awakening came along and to remind us all how much fun an intelligent PC game can be.
The basic idea is simple enough: you have a power supply with a limited number of cores. Aliens will try to walk (and some fly) in and out with one or more of them. Your job is to place defensive towers to kill them off before they reach the exit. The more aliens you kill the more credits to spend on towers you get. Wave after wave even more aliens will come - so you better choose wisely where to place your towers. It seems simplistic but I assure you it is not.
Different aliens require different types of defenses. From projectile and field to short and long range (and numerous upgrades), there is no short supply of defense towers. And since their deployment and upgrades are not instantaneous, you need to plan ahead (there is a tactical screen on top that foretells what kind of aliens are incoming).
As the game progresses there is more freedom in where to place your towers and, subsequently, reroute the aliens' influx. That is really fun! Make them serpentine around your more powerful towers (and delay them with the Temporal Distortion ones) to wipe them out before they even reach your power cores.
The graphics are very well done, with full zooming capabilities. The camera gets a bit jumpy when fast zooming in, a feature I particularly liked because it reminded me of the Battlestar Galactica external shots. The environments are beautifully designed with attention to detail and (contrary to full-priced releases such as Space Siege) never get boring.
I really liked this game. I liked it so much I made sure to buy both expansion DLCs and all four Map packs. If you decide to bite the bullet too, be prepared to get really hooked. This is the most addictive game ever since Civilization II!