Workshop

For example, after winning at the casino at night (and going bankrupt), an ordinary citizen can officially buy it during the day – then the previous owner becomes either an ordinary resident or a drunkard... Or something else along those lines.

Another idea: if two Mafia bosses meet at night (let's say, one goes to kill the other – accidentally, of course), they merge, like in a monopoly. The one who went to kill should remain the leader, and the second, in exchange for his life, agrees to cooperate...
But the downside of this "cooperation" is that only one assassination is possible per night for the two Mafia groups (now effectively one). However, in return, you could add the right to recruit (give it to the former boss).