The game borrows art from PARANOIA XP (the best version, in my opinion) and the mechanics go a long way towards engendering the same rapid switch between truckling subservience to the Team Leader and maniacal glee at blasting that bastard with a plasma cannon because there's nothing left to lose except revenge. Missions are frequently difficult to complete even if everyone is pulling together, and many cards are only useful for painting a target on someone else's back. Further game notes below!
The missions are the principal method to increase your security clearance, ranging from the feasible-with-teamwork (playing "Bake the Traitor"), to the nearly impossible (survive training the Vulture Squadron, hunt mutants in the spent fuel rod depository). They barely matter: much like the tabletop game, the missions are reasons for the team to get into kangaroo courts and shootouts with the survivors either taking all the credit or getting themselves killed during debriefing because they didn't cover their tracks.
Action cards represent weapons, armor, and underhanded schemes that can assign or remove wounds or treason tokens either to the mission or your fellow Troubleshooters. These cards range from the straightforward (laser rifles, hand flamers, lying Really Good) to the outlandish (plasma cannons that assign treason to the user, forcing two players to play cards on each other, etc.). Once a player runs out of cards, the mission ends.
Wounds, treason, and backup clones are tracked with tokens, and the objective is to reach the highest security clearance possible before someone runs out of clones. Increasing your security clearance also makes you harder to kill, harder to mark you as a Traitor, and gives you more cards per round.
Attacking a Loyal player (one without sufficient Treason tokens to mark them as Traitors) earns you treason tokens, and sufficient treason will mark you as a capital-T Traitor - other players can fire on you without consequence, and if the mission (game round) ends with you as a traitor, Internal Security will terminate you regardless of your contribution to the mission.
Treason mechanics go even deeper - "unmasking" a traitor (assigning enough Treason to mark a player as a Traitor) will erase two Treason tokens off your ledger, and terminating a Traitor will erase all of your Treason. This leads a team away from actually succeeding in the mission towards chaotic back-and-forth recriminations and desperate bargaining, just like the finest moments of the PARANOIA TTRPG.