mathogre said:
Assume you have 6 regular players who have a probability of attending a given game of P = .9. The corresponding probabilities of getting n PCs to play is shown below. Only 53% of the time can you expect to have all 6 play.
Simple: If a player can't make it, the character is controlled by the DM or another player for the session. Likewise if two players can't make it. If three players can't make it, cancel.
For a group of four, the same applies, except that we cancel if two people can't make it. (Basically, if player attendence is 50% or less, we cancel. Obviously, if DM attendance is less than 100%, we cancel.
Hers is worse yet. For alot of the time she'll have 3 regular players. Occasionally she might have 6.
It would seem to be fairly dynamic.
In that situation, I would suggest one of two things:
1) Have each of the three players run two characters, with the caveat that one of those characters is 'theirs', and the other is held for another. If one of the three 'irregulars' is present, that player controls their character, and the corresponding 'regular' has only one character that night.
or
2) Structure the game as a series of one-shots lasting a single session each. Have each player control a portfolio of characters, and assemble the team at the start of each session for that night's game. I've found that this approach feels best with a d20 Modern or Shadowrun game, rather than D&D, but it can work here in the right campaign.
This structure does have the massive weakness that it requires every adventure to last exactly one session, which is a lot to ask, and does cut down on the available adventure options a great deal. It also probably works best with less-frequent but longer sessions rather than a few hours on a weekly basis.