Is environmentalism a GAME to you? Does it look like some kind of GAME??? Oh, it doesn't? Well, it could. Upcoming game Anno 2070 lets you go all Sims on the fate of the planet.
You decide up front whether to throw your lot in with the Ecos (who focus on sustainability but progress slowly) or the Tycoons (who focus on aggressive expansion). Either way, your goal is to make civilization grow without completely wrecking the environment (spoiler: the Ecos will probably do better on the second part), while simultaneously weathering the planetwide changes that are already in place by 2070. For instance, you're not just playing to control the surface of the earth — you'll also need to manage underwater societies, because rising sea levels have driven a lot of municipalities under the ocean.
The game has a lot in common with SimCity or Civilization — you manage a lot of complex factors and make compromises in order to meet your goals, and then you sic Godzilla on the whole thing because you're bored. We'll be interested to see whether it's easier to survive as an Eco or a Tycoon, and what kinds of trade-offs the game builds in to those roles.