The Climate Challenge, created by Monterosa Productions, features actors Gael Garcia Bernal, Mackenzie Crook, David Tennant and Ashley Jensen, who answer climate questions under the control of the online player.
The game is available to play at www.theclimatechallenge.org.
It is being launched ahead of the UN climate negotiations in Copenhagen next month, where Oxfam is campaigning for a global deal to protect people from the effects of climate change.
Players will be able to challenge and compete with their friends through Facebook. At the end of each game, players will also be able to add their name to a global petition.
Oxfam hopes the game will encourage people to march at The Wave in London and Glasgow on 5 December 5 to demand that the UK government push for a deal.