The premise behind the gamemode is simple. No one knows their own role or even who they win with. To win, you need to use feedback and the UI to determine your own role and also determine who's on your side and who's not.
Players will only receive three messages when targeting or not targeting someone. "You have decided to target X" or "You have changed your mind." or "You have instead decided to target Y".
The Mafia and Coven no longer have a night chat. They will be able to harm each other with their abilities. The factions still win together though.
There are no special messages such as "You have 3 bullets left" or "The Godfather has ordered you to kill your target" or "You must wait a night before shooting." If your ability has charges, you have no idea if you're about to run out or not.
People will receive feedback from their abilities such as investigative results, your target's defense being too strong, you defending your target from attack, etc.
Roles that can target themselves will see that as an option.
Roles that target two players such as Transporter and Witch/Coven Leader will see that as an option.
Retributionists and Necromancers will simply see no option to target until someone dies.
The Executioner does not exist in this mode.
The Jester will not know they are a Jester and will simply have no ability throughout the entire game, which should give the fact that they are a Jester away.
There are no Death Notes.
Day abilities such as Jailor and Mayor and Pirate function similarly. The Mayor will be able to reveal themselves normally.
Special Interactions:
The Forger will see the blank will pop up when they target someone. That should instantly let them know that they are in fact a Forger.
The Plaguebearer will see who they infected every night.
The Hypnotist will know who they are because they need to select a message.
The Potion Master will need to select one of three potions to use. This will let them know that they are a Potion Master immediately.
The Blackmailer can still read whispers. This will also allow the Blackmailer to know who they are.
The Pirate will see that they need to select the method by which they plunder someone. This will allow them to know their own role immediately.
The Coven will not know that they have received the Necronomicon. It may be obvious to certain roles such as if they suddenly have the ability to target others (Medusa) or if they are now able to select themselves to summon a ghoul (Necromancer).
The Vampire can still convert people. If you are converted, you won't actually know that you are converted unless you see that your ability and targeting has changed. Hopefully, if you are a vampire who just converted someone, you will whisper to them that they were in fact converted. Just be careful that they weren't transported or protected.
Scrolls don't work in this mode (for obvious reasons.) The role wheel animation you get in the beginning is completely replaced with ???s, and you get ???s as your role summary and role name when you enter a new game.
Alternate possibilities:
The Plaguebearer does not see who they infect. It would be extremely chaotic an unexpected for Pestilence to show up, and then you suddenly realize that you've been the Pestilence this whole time.
If the game mode needs to be even more chaotic, potentially all messages that come from other roles can be removed. (The roleblock message, the higher defense message, the transportation message, and the being protected message)
If the game mode needs to be even more chaotic, maybe every player could have the same UI during the night (same as a Transporter's). If your role does not target two people, only the first target will be used. If you select to target yourself when you can't, your ability will simply not work.
If the game mode needs to be even more chaotic than that, then additionally, you could add in random investigative results every single night for all players. That means everyone will get a random Investigation message, a random Sheriff message, a random Psychic message, a random Consigliere message, and occasionally a Tracker or Lookout message. Only for actual TIs (and Witches/Coven Leaders and Consiglieres) will the message they get for their role be real. However, this includes an element of RNG in the game. (You could have really promising investigator results suggesting you are in fact an Investigator when you're not, or you could have results that are obviously fake and allow you to instantly know you are not an investigator.)
Role list for Classic:
Jailor
Investigator
Town Investigative
Godfather
Consort
Consigliere
Random Mafia
Doctor
Escort
Town Protective
Town Killing
Random Town
Random Town
Arsonist
Neutral Evil
Role list for Coven:
Jailor
Sheriff
Survivor
Coven Leader
Poisoner
Hex Master
Random Coven
Crusader
Town Protective
Transporter
Random Town
Random Town
Retributionist
Random Neutral
Pirate
Complete Chaos (an option in both Coven and Classic):
15 Any slots
Notes:
With the total lack of information, there are serious risks to consider whenever choosing who to target, especially if you don't know what your role is. For example, if you don't have an option to target n1, and you reach n2 and you do have an option to target, that could mean you're a Trapper, Werewolf, or Vigilante. Think about those possibilities before just straight up targeting someone. Instead of protecting the Psychic claim, you could be just straight up shooting them. If you can target anyone including yourself, that could mean you're a Doctor, Bodyguard, or Arsonist. Remember to narrow the possibilities for your own role down while keeping track of what other people are saying they received as messages.
In the early game, TIs dominate. Not only can they provide feedback on what other roles do, they almost instantly know who they themselves are. In the Mafia, the Consigliere is extremely important, as they can gather information about who their fellow mafia and begin whispering while pretending to be a TI role. In the Coven, the Coven Leader fulfills this role by controlling people and determining who's on their side. Beware that the Coven Leader will begin killing their targets after n3 though.
The fact that no one knows what their role is allows you to pull off some short term trickery. For example, if you are the Coven Leader, you may be able to convince a Crusader that they are actually the Hex Master. If you're a Consigliere, you might be able to convince someone that they are the Consort when they are actually the Escort. (Note: In fact, as a Consort or Escort you have no way to judge who you really are unless an investigative role communicates with you.)
Messages are the main way people can decide their own role. Lying about messages you received (etc. pretending to have been healed or role-blocked or trapped or even "Attacked but your defense was too high") can confuse players and make them believe they are a role that they are not.
In general, the game is extremely chaotic in the early stages and settles down as people discover what their abilities actually do.