I want a game that starts out on a nice, beautiful little idyllic planet, inhabited by various species of aliens that are able to peacefully co-exist and live together in harmony, just as an interstellar invasion fleet warps into their system, their orbital defences are obliterated by nuclear strikes and an army of evil, dastardly humans land on the planet, hell-bent on obliterating the lot of them.
Then you take the role of one of the human soldiers, slaughtering technologically inferior aliens on their turf.
Either that or a Beyond Civilization game. Starting again in Post Apocalyptica, rebuilding your civilisation, then taking on the other various civilisations of the world, all of whom believed you totally started it. Complete with raiders, mutants and an incomplete tech tree that changes from game to game, relying upon negotiated/stolen tech from other civs and hidden underground research labs full of pre-war goodies to fill in the gaps. Your standard victories apply - conquest, diplomacy, tech - except that the tech ending branches off, giving you the option to invent the Genesis device to restore the planet to it's former glory, thus making everyone love you, or get your arse to Mars, where there's a nice stockpile of interplanetary warheads that were abandoned before the war, which you can then use to obliterate the last of your enemies, but causing a new apocalypse.