Not much info here. A variant with a Mao Master , who assigns all the penalties and is the only one to make new rules. Pagat Rules of Card Games listing for Mao. Has more links. Good for looking up other games, too.
Every rule has a good reason for being in the game.
Most rules are in the game to confuse the players, which is the point of the game. Playing groups should be encouraged to make their own house rules to add to the game and should pick a handful of rules from the optional rules presented here. Bullshit, Asshole, and Mao are party games that require not thought but attention. Please mention how you found me, your URL, and comments.