In Terraforming Mars, you control a corporation, and you buy and play cards describing different projects. The projects often directly or indirectly contribute to the terraforming process, but can also consist of business enterprises of different kinds. In order to win, you have to accumulate a good Terraform Rating (TR) and many victory points (VPs). Your TR is increased each time you raise a global parameter (temperature, oxygen or ocean). Your TR determines your basic income, as well as your basic score. As the terraforming process proceeds, more projects become feasible. Additional VPs are awarded for anything enhancing mankind’s grip on the solar system. This can be anything, from founding cities to building infrastructure, or protecting the environment.

In order to win, you have to accumulate a good Terraform Rating (TR) and many victory points (VPs). Your TR is increased each time you raise a global parameter (temperature, oxygen or ocean). Your TR determines your basic income, as well as your basic score. As the terraforming process proceeds, more projects become feasible. Additional VPs are awarded for anything enhancing mankind’s grip on the solar system. This can be anything, from founding cities to building infrastructure, or protecting the environment.

Time is measured in generations, and each generation starts with a Turn Order phase, followed by a Research phase, in which players access new cards. In the Action phase, players take turns doing 1 or 2 actions, going around the table until everyone has passed. Then, in the Production phase, all players produce resources according to their production parameters on the player boards, and gain income from their TR.

The central game board has tracks for temperature, oxygen level, Terraform Rating, and generations. There is a surface map where you add ocean tiles, greenery tiles, and city tiles as the game progresses. There is also a list of standard projects available to all players, as well as milestones and awards that players can compete for.

The game ends when there is enough oxygen to breathe (14 %), oceans enough to allow Earth-like weather (9), and the temperature is well above freezing (+8 ˚C). It will then be possible, if not comfortable, to live on the surface of Mars!