Rules

One person (who will be the host) will need to start a game, after which they will be given a game code they can share with the other players who can then use this code to join the game.
Once all players have joined, the host can close registration. The app will then select the players to be traitors. Depending on how many players there are, there will be a different number of traitors to start with - more than 13 players = 3-4 traitors, more than 9 players = 3 traitors, more than 5 players = 2 traitors.
The traitors must keep the fact that they are traitors, and the identity of their fellow traitors, a secret.
Players who aren't selected as traitors will be faithfuls.

Once traitors have been selected, they will commit a murder, eliminating one of the faithful.
Traitors must unanimously agree on the person to be murdered.
After each banishment, there will be another murder.

After each murder, there will be a banishment vote which is the only opportunity for the faithful to eliminate a traitor from the game.
All players who are still in the game must meet (in person or online) and discuss who they think the traitors are. Having discussed, each player must vote to banish another player.
Who voted for who will be revealed to all players along with the result of the vote.
Draw
If the vote results in a draw, all players should discuss again before voting again. This time however, only the players who were tied with the most votes will be eligible to be voted for.
If after this vote the result is still a draw, the banishment will be left to chance and one of the players who received the most votes will be selected at random and banished.

If a banishment results in there only being 1 traitor left, they will be given the option to recruit another player. Whether they chose to recruit or not, they will be able to commit a murder afterwards.
If the traitor decides to attempt to recruit, they will send an invitation to one of the faithful. The faithful player will then be given the option to acaept or decline the invitation.
If the faithful accepts, they will become a new traitor and be able to join the existing traitor in committing a murder straight away. If they decline, they will remain a faithful.

When a banishment leaves 4 or less players, the game will move to the End Game phase.
In this phase, each player will have to decide if they believe that all of their fellow players are faithful or not. If they do, they can vote to end the game, in which case the game will end immediately. If they don't, they can vote to have another round of banishment. Once all players have voted, the votes will be revealed. To end the game, all players must vote to end the game. If 1 or more players vote to banish again then there will be another banishment vote.
The game will only end once all players vote to end the game, or there are only 2 players left.
Once the game has ended, it will be revealed which of the players that are left were faithful and which were traitors and therefore whether the faithful managed to eliminate all the traitors, winning the game.