A player who leaves the game doesn't participate in the game anymore. So all his cards should be discarded in the box and game should actually become 1 player less with all rules applied to less amount of players. All pacts with the player left the game should be discarded. He shouldn't produce any resources, culture and scince points, shouldn't take any cards from the rows. On other players turns number of cards discarded from the left should correspond new number of players.
On BGA these rules are not enforced.
On BGA these rules are not enforced.