All you need to do a good Duke Nukem series is to rip off the plot of Demolition Man, but replace Simon Phoenix with aliens.

Humanity in the future has become soft and gay, and they can't repel an alien invasion, so they have to get Duke out of cryostasis (or clone him, or go back in time to retrieve him, insert whatever contrivance necessary). Everyone is ultra PC and offended by everything he says, but he kicks ass and chews bubblegum, and gum became illegal in 2067.