This is an expansion! A copy of Terraforming Mars is required for play. 

As the mega corporations are getting ready to start the terraforming process, you now have the chance to make those early choices that will come to define your corporation and set the course for the future history of Mars - this is the prelude to your greatest endeavors!

In Terraforming Mars: Prelude, you get to choose from Prelude cards that jumpstart the terraforming process or boost your corporation engine. There are also 5 new corporations, and 7 project cards that thematically fit the early stages of terraforming.

Terraforming Mars: Prelude is the third expansion to the smash-hit game, Terraforming Mars, and can be combined with any other expansion or variant.