Ares Expedition: Crisis is a brand-new game mode that uses the mechanics of the original Terraforming Mars: Ares Expedition in a challenging new way. Play it solo, or band together with up to three friends to work together to save Martian society after a catastrophic asteroid collision has taken out nearly all of your infrastructure.

In Crisis Mode, the planet is already terraformed, but ongoing fallout from the impact is dropping temperatures, de-oxygenating the planet, and freezing over oceans, and there's no time to evacuate the entire global population. You must work fast, completing projects to counteract the ongoing crises and re-terraforming the planet before it becomes uninhabitable. . .with billions of people still on it. 

This is not a stand-alone game, a copy of is required to play.