From The Dim Future Wiki

Factions define the game world allegiances and skills known by a given group of people.

A player cannot play an Action, or Installation that does not share a faction with their leader.

A player can only attach a tool to a character that shares a faction with it.

To play a character that does not share a faction with a player's leader they must pay 2 extra energy of the character's primary energy type. This energy is not needed to restore the character. In addition, if the player ever fails to pay the character's restore cost it is immediately and permanently removed from the game.

Each of a player's areas must share a faction with their leader. If any area does not, the deck is illegal.

Any card with no printed faction is considered to have all factions. This is referred to as being factionless. Factionless cards can be played by any leader with no penalty and, in the case of tools, can be associated with any character.

The four initial factions are:

Also there are factionless cards.