Basically, the best and brightest people flee earth to a planet in orbit around Alpha Centauri prime shortly before a massive nuclear war. After some misadventures involving a terrorist organization, an assassin, a damaged fusion reactor, and some other stuff, they split into seven factions and start cities on the planetary surface, at which point they come under attack by indigenous mindworms and fast growing xenofungus. It turns out the fungus is sentient and controls the mindworms and their naval, aerial, and, in the expansion, artillery and submarine variants.

Since it's a civilization style 4X game, the exact ending is up to the player, though the consequences of the conquest, diplomatic, and economic victories are somewhat unclear. Basically, the humans merge with the planetmind, get eaten by mindworms, or burn, poison, and nuke the fungus back. Alternately, in the expansion one of the alien factions calls in home fleet.

I wouldn't mind one of the minis, or a mutated wolf (or both) and the snow here all melted away...