You win the game by having the most Victory points (VPs). VPs are scored for your Terraform rating, from tiles on the map, from Milestones and Awards, and from many of the cards.
Terraforming Mars is about making Mars earthlike enough to live freely on it. There are 4 parameters on the game board connected to this process: Terraform rating, temperature, oxygen level and ocean coverage.
Terraform Rating (TR) is the measure of how much you have contributed to the terraforming process. Each time you raise the oxygen level, the temperature, or place an ocean tile, your TR increases as well.
Each step of TR is worth 1 VP at the end of the game, and the Terraforming Committee awards you income according to your TR. You start at 20.
The mean temperature at the equator is raised 2 °C at a time from -30°C to +8°C. This will create an equatorial zone where water stays liquid. This symbol means that you raise the temperature 1 step, and therefore you also increase your TR 1 step.
The oxygen level is measured as a percentage of an atm of pressure, meaning that this percentage is comparable to Earth's 21% oxygen. At 14% the atmosphere resembles that of Earth at a 3000 m elevation. This symbol means that you raise the oxygen level 1 step, and therefore also increase your TR 1 step.
Each ocean tile represents 1% ocean coverage.
With 9% of the surface covered by oceans, Mars will have a hydrological cycle, creating rain and rivers. This symbol means that you place an ocean tile, and therefore also increase your TR 1 step (and get any placement bonus).
All resources are represented by resource cubes.
These come in 3 sizes; 1 (bronze), 5 (silver) and 10 (gold) and can be used as any kind of resource. Where you place them determines what they are. The six standard resources are megacredits, steel, titanium, plants, energy and heat, and they are all collected on the player board. Certain cards can also collect resources (usually animal and microbe cards). If a card adds a non-standard resource, it is generally placed on that same card.
The MegaCredit (M€) is the general currency used for buying and playing cards and using standard projects, milestones, and awards.
Steel represents building material on Mars. Usually this means some kind of magnesium alloy. Steel is used to pay for building cards, being worth 2 M€ per steel.
Titanium represents resources in space or for the space industry. Titanium is used to pay for space cards, being worth 3 M€ per titanium.
Plants use photosynthesis. As an action, 8 plant resources can be converted into a greenery tile that you place on the board. This increases the oxygen level (and your TR) 1 step. Each greenery is worth 1 VP and generates 1 VP to each adjacent city tile.
Energy is used by many cities and industries. This usage may either be via an action on a blue card, or via a decrease in energy production. Leftover energy is converted into heat.
Heat warms up the Martian atmosphere. As an action, 8 heat resources may be spent to increase temperature (and therefore your TR) 1 step.
Other resources (including animals and microbes) are collected on their respective cards, which also define what they do.
Production of a resource is depicted by having the resource symbol in a brown production box. In this example the symbol means that you increase your plant production parameter on your player board 1 step. This in turn will give you a steady income of plant resources. Production is not limited to 10; if your production exceeds 10, just leave the marker on 10 and start a new marker to complement it.
Only M€ production can be negative (only as far as -5, though). But since TR is added to your production, your total income will not be negative.
Cards represent huge endeavors that players may undertake. The cards have 0-3 different tags that describe some thematic aspects of the card, and that can be utilised in conjunction with certain other cards. Cards cost 3 M€ to buy into your hand during the research phase, but have different costs to play from your hand into play. When you encounter this symbol, it means that you may draw a card to your hand (without paying for it).
Cards have 0-3 tags that thematically describe them and allow other cards to relate to them. There are no special rules for the different tags.
Building: This project involves construction on Mars. Steel may be used to pay for this card.
Space: This project uses space technology. Titanium may be used to pay for this card.
Power: This project is focused on energy production or handling.
Science: This project enhances your scientific knowledge. Some cards require science tags.
Jovian means 'having to do with Jupiter'. This project r+epresents infrastructure in the outer solar system.
Earth: This project is related to activities on Earth.
Plant: This project involves plant life or other photosynthesizing organisms.
Microbe: This project involves microbes for specific purposes.
Animal: This project involves animals. Generates VPs.
City: This project places a city tile. This often requires energy production and produces M€.
Event: This project is a one-time event. All events are red cards that are turned face down after being played.
The game board has a map where tiles may be placed. When placing a tile, you may receive a placement bonus printed on the area (plus 2 M€ for each adjacent ocean). There are 4 kinds of tiles:
This symbol means that you place an ocean tile. This increases your TR 1 step. There are 12 areas on the game board that are reserved for ocean tiles; Ocean tiles may only be placed on such areas and no other tiles may be placed there. Ocean tiles are not owned by any player, but generate a 2 M€ placement bonus each for any player subsequently placing tiles next to them.
This symbol means that you place a greenery tile with an owner marker (this also increases oxygen level and TR, as indicated by the oxygen symbol).
The tile must be placed next to another tile that you own if possible. If you have no tiles or no area next to them, you may place it on any available area. Greenery tiles are worth 1 VP at the end of the game, and also generate a VP to any adjacent city (see city tile rules).
This symbol means that you place a city tile with an owner marker. The tile may not be placed next to another city tile. Each city tile is worth 1 VP for each adjacent greenery tile (regardless of who owns the greenery tile) at the end of the game.
Symbol tiles in brown mean that you place the special tile described on the card, with an owner marker. Any special rules and placement restrictions are specified on the card.
Red Border On Icons
When an icon has a red border, it means that it targets any player (you or an opponent).
A card that removes red-borded resources, may remove those resources from any one player (this effect may also be performed partly, or not at all).
A card effect that reduces production of a redbordered resource must be performed, so if your opponent doesn't have that production, then you must lower your own production or not play the card at all.
A card with a red-bordered tile icon targets any or all players' tiles.
A card with a red-bordered tag icon targets all cards with that icon, whether they belong to you or another player.