Basically everyone gets a role. That role can be Town, Mafia, Indie, etc. Each role has a faction. If you're Town you have to talk and identify the Mafia by discussing in the thread and get rid of them. If you're Mafia you have to hide and blend in with Town until all Town are killed off. Indies have separate win conditions. A Serial Killer has to kill everyone. If you play, you have a day phase and a night phase. Day phase Town have to find Mafia and Mafia have to avoid capture and suspicion. Night phase is when Mafia kills. That's the gist of it.