Mafia Game Rules

[callforjudgement]

You can change during signups, but not change in a game-related way during the game (I'd consider that to violate the "communication about ongoing games" rule).

Changing during signups is fine because the game isn't ongoing at that point.

As for the question in the OP, Callforjudgement's Standard Rules is my full list of rules, plus explanations of the motivations behind them.