GTA: Fortress Magnus
In ancient times, aliens attack the world and they thought that mankind has no defense against them since they were primitive. But, that is where they are wrong since man has this flying fortress known as Magnus. This fortress not only has the ability to fly, but also has enough weapon to eradicate the aliens. Do battle with the alien fleets that want to do harm to the world. Shoot them from out of the sky till they are all gone. Some ships will drop coins and if you hover on it with your mouse, you can gather them. You can use the money to upgrade your fortress.