From zombie plagues, and star troopers to the world of four color comics, this is why I intend to use the USR system when presenting this menu of choices to players. I'll need a completely flexible game system to follow the whim of player choices.
Space Opera Genre Tree;
2.1 Post Apocalypse 2.2 Comic Books 2.3 Hard Sci Fi
Space Opera, Post Apocalypse;
Post Apocalyptic story arcs never go out of style, and once again, your sources of inspiration to be found in film alone are immense. I for one am mashing up Aos' material from his fantastic blog Metal Earth with my love of Kamandi, the last boy on Earth DC comics series. This mash up would be my Space Opera, Post Apocalypse campaign setting. Though there are significantly more world settings to be had. The popularity of The Walking Dead television series not withstanding, different "collapse" scenarios are numerous, and all have particular story needs.
This branch of the Genre Tree should demand more background material be forth coming from the GM for the players to orient themselves in their game world. Even if it is a narrow band of non polluted ground, the players should have a handle on how they have survived in this hostile world. What has allowed them to live while others die.
Die hard Gamma World, and Mutant Future fans will find their favorite story lines here, and should be prepared for the shocking deaths their PC's will find. This does not preclude civilizations anchored on the long dead carcass of a past world to be flourishing, but the effect of some disruption is embedded in the culture.
2.1 Space Opera, Post Apocalypse;
2.1.1 Future Shock
2.1.2 Living Dead Dominion