Defense Grid: The Awakening
Defense Grid: The Awakening is a tower defense game, in which you control the placement of various kinds of towers and defend against the invading aliens. The aliens come in waves, and as the game progresses the aliens become more powerful and more numerous. The game consists of a number of missions, each of which is to be completed in succession by defending the power cores from the aliens.
There are several types of towers, each with its own strengths and weaknesses, and each of which can be upgraded to increase its effectiveness. Placing and upgrading towers costs resources, which can be gained by destroying the aliens, or from interest on your current stock of resources. In addition to the towers, the player will acquire an orbital laser which can be fired, rarely, to destroy the aliens at its point of impact immediately, with the drawback that no resources will be gained from them.
If the player can complete the missions successfully, he will be awarded a medal (bronze, silver, or gold) for completing the mission, based on the number of cores that remain, as well as the number of points acquired. Completing missions unlocks later missions as well as alternate play modes for the mission completed, such as a challenge mode with more powerful aliens or a mode in which only a limited number of towers can be placed.