Terraforming Mars Ares Expedition: Discovery adds four new mechanics to the Ares Expedition base game: awards, milestones, upgraded phase cards, and wild tags.

Awards are points awarded at the end of the game to the player with the most of something. Three awards are drawn at the beginning of the game so players know what they will be rewarded for at the end of the game. The player with the most of that item receives 5 points, second place receives 2 points.

Milestones are points awarded during the game. They are awarded to the player who first achieves the milestone. Milestones are worth 3 points at the end of the game.

Some new project and corporation cards allow players to upgrade their phase cards. Each phase card has two different versions that players choose between when upgrading them. The upgrade gives the player a better bonus when choosing that phase.

Some new project cards have a wild tag. When a player reveals this card either from the deck (due to an effect) or from their hand because they are about to play it, the player chooses which tag they want it to be. Markers are used to keep track of which tag was chosen for the rest of the game.