Nuclear Mode is a game mode in which the crew of Space Station 13 must fend off a group of agents from the Syndicate trying to invade the station by force to detonate a nuclear bomb. The Syndicate Agents start with the bomb and any equipment they decide to take with them from the Syndicate Station, but need an Activation Disk in the posession of the Captain in order to arm it.

The Crew and AI must kill all Syndicate Agents and prevent the disk from falling into their hands.

The Syndicate squad must get the bomb onto the station, find the disk to activate the bomb, then flee before they are consumed in the blast.

If the Syndicate are consumed in the blast, they fail their mission, so nobody wins. But it all depends on the captain...