The game takes place over several "generations" as the players research projects (cards), spend their funding on making those projects happen, and acquire the resources and support to take larger and larger steps towards making the planet livable. Mars needs three things oxygen, a higher temperature, and a working water cycle. Contributing directly to any of these will increase your score and raise more government funding. Creating your own infrastructure whether industrial, space-bound, economic, or biosphere - will aid your efforts and give more opportunities to score, as will some good PR for hitting the right milestones. The game ends when Mars reaches a threshold of "uncomfortable, but habitable", and the winner will be forever known as the leading pioneer of Mars.
The game has received a range of Expansion Packs:
- Hellas & Elysium introduces two new maps to play on. Hellas features a cold south pole that can be terraformed for heat and water, while Elysium features Mars' highest peak, which provides a large boost to research once terraformed. Each of these maps features their own milestones and awards.
- Venus Next introduces Venus as a planet that cities can be constructed on, 49 new project cards, 5 new corporations, a new milestone and a new award.
- Prelude includes 5 new corporations, 7 new project cards, and a new phase at the beginning of the game that allows you to improve your resource production or terraforming progress before your first turn.
- Colonies includes 5 new corporations, 47 new project cards, and a new mechanic involving trading with colonies across the solar system.
- Turmoil, alongside new corporations and project cards, introduces a new political dimension of the game that players must attempt to influence and play around.
The game also had a Card Game version called Terraforming Mars: Ares Expedition.
The game contains examples of following tropes:
- Absent Aliens: Due to the game's (relative) realism, no Martians show up. At most you'll find some local bacteria through the "Search for Martian Life" project.
- Boring, but Practical: The "Martian Rails" card is not exactly what you'd call cutting-edge science fiction — but it provides income in proportion to the total number of cities built on Mars, and can be pretty powerful in the middle-to-late game.
- Climate Change: Causing this is one of your goals. It can be done through asteroid impacts, by releasing volcanic energy, or just through good old-fashioned greenhouse gases.
- Colonized Solar System: Strongly implied to be the setting. Several resources are shipped from Jupiter's and Saturn's moons, so there should have to be at least some bases that far out. This is made explicit in the Colonies expansion, which focuses on the outposts throughout the system.
- Cool Airship: You can use them for transportation. They have a similar effect to the Boring, but Practical railways, but they cannot be built until the atmosphere has been thickened a bit.
- Corrupt Corporate Executive: You can play as one! Specifically, you play as the head of a corporation, and you can choose to take ethically questionable actions, such as using indentured workers or sabotaging other companies. However, the opportunities for outright evil are relatively limited; presumably, law enforcement is effective enough that blatant Corporate Warfare is bad business.
- Crutch Character: The helpfully named Beginner Corporations let you keep all 10 research cards that you draw at the start of the game without paying their costs. This is very useful for simplifying the early portion of the game if you're learning to play, but the Beginner Corporation's lack of a special ability beyond that, or any tags that can speed up research, makes it less useful for a player who better understands how to manage their resources.
- Domed City: Early cities on Mars are by necessity domed. A project playable late in the game can construct the first open-air city, with a bonus to income and victory points.
- Euro Game: One actually created by a European company. Terraforming Mars has most of the usual Euro features, such as a relatively low random element and an emphasis on resource management, though it is more strongly themed than some, and the art is a bit erratic by Euro standards.
- High-Tech Hexagons: It may be coincidental, but the game's tiles are hexagonal.
- Mohs Scale of Science Fiction Hardness: Rates near a 5 most of the proposed projects are theoretically possible, just not currently possible with available technology. One or two of the most advanced are a bit Space Opera, though they do require that the player has done a lot of science first.
- Orbital Bombardment: There are quite a few positive ways to affect Mars that would normally fall in the planet killer category if used on Earth. Hitting Mars with a comet will produce water, for example, or you can set up shop on a radioactives-rich asteroid and use laser beams to heat up the atmosphere.
- Settling the Frontier: One card lets you set up an immigration center to speed up the flow of travelers and settlers.
- Shout-Out: In the manual, the examples of how the game works involve a hypothetical game between three players named Kim, Stanley, and Robinson.
- Space Elevator: One of the more expensive projects you can build, which gives a considerable boost to your economy.
- Space Station: You can build one to decrease the cost of all other space-based projects.
- Terraform: The Board Game.
- Timed Mission:
- While there are no hard time limits in the standard game, some cards cannot be played after the terraforming reaches a certain threshold — like the search for Martian life, which can only be done while oxygen is low, or the release of super-cold-adapted organisms, which is impossible above a certain temperature.
- The solo variant does have a time limit. Your goal is to complete the terraforming of Mars within 14 generations. There isn't a 15th generation, whether you complete your objective or not.
- We ARE Struggling Together: Avoided for the most part. There's a lot to do over a lot of time, so projects concentrate on the positives. That said, there are occasional opportunities for stealing your rivals' thunder that comet may incidentally impact a competitor's plants, the predators you introduce may not be too picky about whose animals they feed on, you might bump the oxygen or heat level just a notch out of bounds for a competitor's card, or you might simply have a rival build their city in the sweet spot where you were just about to build YOUR city. The Turmoil expansion adds an explicit political element, with competing factions for the players to support.