Characters of Absent Players: If a player is absent, their character will be faded into the background. The DM may contact the player ahead of the time for input on any group decisions, but otherwise, the character is out-of-play.
Cancellations: If more than 1/3 (2 of the 6 players) are absent, the session will be cancelled. If the DM deems a session to require all players to be present, the session will be cancelled if any players are absent.
Makeup sessions: Typically, a cancelled session will be a cancelled session. However, if special circumstances warrant a make-up session (e.g. holidays providing additional availability), the DM will contact players to arrange an alternate game date.