All this discussion has given me the perfect idea... and it is perfect, so any criticism will be filed under 'jealousy, that you didn't think of it first'
Call of Duty: Civil War... in SPACE!
Plot: The year: 1868. The Confederacy's most militant obsessive scientists have been working on a device to turn back time so they can gain the advantage and return to the glory days. Their experiments are nearly complete when Union spy Catherine "Slasher" Goodebody discovers their plot. Goodebody, uses her charm, wit, and ridiculous video-game female body to sabotage the experiment... but not everything goes as planned when she falls in love with a reluctant scientist now ready to leave the project.
Flash forward, the year: 2047. General Lee and Grant's armies are transported along a wormhole into the Icarus Space Station in deep space. The massive station at first seems like home to the warring factions and they fight furiously to gain the upper hand so that they, victorious, can control the massive death laser and turn it against their foes hundreds of light years away on earth after turning time back.
Little do they know...
Both armies now depleted, must band together to fight a new foe. A foe so evil, so insane, so horrible they can hardly imagine... Nazis, zombie Hitler, and a group of militant pedophiles find the device a hundred years after its original use and transport themselves to the same space station.
Now.... this game has everything. Civil War, Zombies, Space, Modern weapons, WW2 weapons, Future weapons, evil, intrigue, explosions, a hot female character, plot twists, time travel, lasers, badly executed accents, and so much more.
Target revenue for first weekend: 1.26 Billion USD
Your compliments are appreciated as are job offers from Hollywood or the game industry.
Keep your jealous criticisms for yourself. This idea IS perfect.