"Endgame" obviously refers to the events that occur near the end of a Mafia game.
As a Noun
"Endgame" is differentiated from "lategame" as the last chance the Town has to avoid losing. Typically, this is when the number of living Townies is at most two greater than the number of living scum (commonly called Eliminate-Or-Lose, or ELo). However, in games with multiple kills or power roles that could command the next Day on their own, it could also refer to the last Night as well.
Some moderators will explicitly state if the current phase is ELo; however, this is not common practice on mafiascum.net.
"Endgame" is never used to refer to a situation where any faction other than Town is about to lose, as a game with only one scum remaining can drag on for multiple Days.
As a Verb
"Endgamed" is a shorthand for saying "killed in the endgame". This will occur when absolutely nothing can be done to prevent a particular faction from winning. The standard Win Condition for Towns, Mafias, and Serial Killers is to be the only faction alive; this is accomplished when all of the following are true:
- In the case of non-Town factions (called Mafia from here on even though the same applies to other factions), the Mafia must control at least 50% of the votes in play. In this way, the Mafia can prevent members of their own faction from being eliminated during the Day.
- All killing roles not allied with the winning faction must be dead UNLESS it would be impossible for them to make a difference. If any form of scum are alive, Town cannot win. If Mafia control 50% of the votes going into Night but a Vigilante or Serial Killer are alive, it is situationally possible for a member of the Mafia to die overNight and thus lose their majority.
- In the case of the Town, all players who cannot win with Town must be dead. This rule is in place because setups do exist where scum groups do not have night-kills, but must still be eradicated before Town can win.
Here are a few examples for clarification.
- There are five players alive: Three Town, two scum. Suppose one of the Townies is miseliminated and neither of the other two Townies are Vigs. The remaining Townies are endgamed, as scum controls 50% of the votes and there are no killing roles aside from them.
- There are six players alive: Four Town, two scum. Suppose one of the Townies is miseliminated and there are no relevant power roles. The remaining Townies are endgamed, as after their kill scum will control 50% of the votes and there are no killing roles aside from them. It is assumed that scum will kill if it will win them the game and it does not make a difference who they kill.
- There are six players alive: Four Town, two scum. Suppose one of the Townies is miseliminated and one of the Townies is a Doctor. The remaining Townies are not endgamed, as it is possible to prevent the scum from having 50% of the votes during the next Day (if the Doctor successfully protects against the Mafia's kill).
- There are seven players alive: Four Town, two scum, and an SK. Suppose one of the Townies is miseliminated. The remaining players are not endgamed; as even though Mafia controls 50% of the votes, the SK can kill one of the scum overNight to bring the game to 2-1-1.
See also Bulletproof for another case of role interactions with endgame.