>>12983063border defender with each level in a different country.
keep it a simple shooting gallery with insane weapons and quick levels.
>sink immigrant boats with your minigun mounted on the white cliffs of dover>use an orbital ion cannon to sink immigrant boats off the coast of italy>nuke the entirety of apefrica and india with your spaceshipyou get the idea. it would be epic and you could have powerups and stuff. just one man with insane weapons