A good shooter, City Siege 3 - with an upgrade available units. Control mouse and keyboard (WASD + LClick). You can buy more different units that have their own function. For example there is a spy - its difficult to see the enemy. Any military veteran - he fires a mortar. There are also tanks, helicopters, anti-aircraft rocket launcher. And one of the favorite units - commandos. The game is fun to play if you like shooters.