How does ELO work if a player prematurely leaves the game?
Games that are quit prematurely are calculated as losses. The player who leaves the game first will receive ELO deductions as if he lost the game.
This is not affected by the current position in the game at the time the games has been forfeited.
If other players drop out of the same game they will be placed according to the time they quitted. Based on this placement the ELO will be calculated.
The last remaining player will gain ELO as if he had won the game. The calculation does not take in account which place he finished in the game (against the AI).