Age of Glory

Age of Glory is a tower defence game that is simply awesome.  The game is multiplayer but you can always start this tower defense game alone and see how long you can survive.  Build up your tower defenses and stop the creeps from exiting your map.  Don"t only focus your tower defenses in one area.  Use your mouse to scroll through your map to make sure you have towers and turrets to set up defenses that cover your entire area.