And then there is the campaign which presents a series of missions to accomplish. The missions are structured in six series of ten phases. Each is quite short, a few minutes of action at most. You can save your play at any point so this is a game that you can play in short bursts if you wish to. Missions are action packed, with a lot of varied alien craft involved.
Some missions even attempt to add a bit of variety in the mix.
You have the task of destroying incoming aliens to defend something, offensive strike missions, escort missions, even missions to grab something and move it somewhere. You control your vehicle, be it tank, plane, what have you, using the keyboard. You can change your orientation, left right, up down, rotate and change altitude. Control varies by the type of vehicle you are piloting. In no case is it easy to control.