Okay. I was putting some more thought into the Monopoly idea, and came to the conclusion that it needs to be a Mafia game specifically. I'll need to figure out what sort of roles would be included, but I did nail one down straight away.
Also, there will be 2 "dead" zones, but they function the same way. The town will act as a jury every day, and vote to convict (go directly to jail). At night, the Mafia will frame an innocent bystander who will also be sent to jail. Mr. Monopoly can't send you to jail, but he'll take all your stuff and you'll be homeless, having lost the game.
Making this more of a depression era game, when the Mafia was also especially rampant, the other "dead zone" will be Hooverville (shanty towns built during the great depression). This is where you'll go if Mr. Monopoly seizes your assets. This is also where you'll go if you're a townie who is put on trial (voted out by the other city folk) - unfortunately your lawyer fees were too high so you had all your stuff repossessed to pay for it all and now can only afford to live in Hooverville.
Mr. Monopoly
Mr. Monopoly is the representation of pure capitalism. He doesn't care about his community OR the Mafia. All he cares about is getting as much for himself as possible. His goal is to be the last one standing, owning the entire board to himself. Once per night he can perform a hostile takeover on one other player, seizing all of their assets and evicting them to Hooverville. Cannot be targeted by the Mafia because he has too much at his disposal to be able to be framed.
The Village
The player tokens will be villagers (or in this case "City Folk"). Need to figure out what roles might be in there, if any. For roles on the City Folk side though, we'll have
Chance Card(s)
One or two, haven't decided yet. Each night, they can issue a "Get out of Jail Free" card to a player of their choosing. This player will be protected from any night attacks. Once during the game this player may elect to use an "Advance to Go" card to prevent a lynching by sending that player into the night phase safely (PMs the DM), if this ability is used during the day, they cannot use their protection ability at night. (this might be better as two separate roles, but for now I'm leaving it written as one)
There's also the "Go Directly To Jail" card that's in this bucket, so this could also be broken out as the Vigilante role too.
Community Chest
I want some sort of "medium" style role in this game, and this set of cards has one that might work: "Bank Error in Your Favor: Collect $200" - This player communicates with the occupants of Hooverville, and once per game may issue the bank error. This will give that player enough money to come back into the game.
The Mafia
This side needs some work. Happy to take any suggestions here.
None of this is final (other than probably Mr. Monopoly). Just some ideas I've been tossing around.
edit:
@Cole because I know you love Monopoly and probably have a bunch of useful thoughts here.