Terraforming Mars: Prelude is set before the corporations begin the transformation of Mars depicted in the main game (see “Stronghold Games Takes on the Red Planet”), allowing them to customize their corporations. Each player is dealt four “Prelude” cards from which they select two bonuses to improve their corporation or get a head start on their terraforming operation. In addition, the expansion offers five new corporations for players to play, as well as seven new project cards that focus on the earliest stages of the terraforming process.