One thing I really liked in AH was the playable cultist. Working against the team was one of the funnest parts in large group games.
I have been thinking of ways to implement the cultist in group games. Let me know what you think.
Minimum 5 players to use the cultist.
Randomly determine which player would be the cultist in secret.(random drawing)
Everyone draws an investigator as normal.
One person secretly is the cultist.
During each players turn, they may use thier "resolve an adventure" step to call a person out that they suspect may be the cultist
If they are wrong, an elder sign is lost. If they are right, the person reveals they are the cultist and can no longer assist on adventures.
After being revealed, for every elder sign rewarded to the cultists after completing an adventure, is instead deducted from the total amount of elder signs collected by the investigators.
Winning and lossing:
If an investigator playing a cultist manages to stay "hidden" until the deep one awakens, he is removed from the game(the clock will not strike on his "turn") and adds an additional doom counter to the doom track, surpassing the maximum number of doom counters normally allowed. If all the investigators are defeated, the person playing the cultists is considered the winner.
If an investigator playing a cultist has been revealed and the deep one awakens, the cultist is removed from the game (the clock will not strike on his turn). If all of the investigatos are defeated, the cultists is considered the winner.
If the investigators collect enough elder signs to win the game or defeat the deep one, the cultists must reveal him/herself if they haven't already, and is considered the loser of the game!