The last player who played meaning the player who is the fartest behind on the player order track.
Two of us just tied tonight in a three player game. Both of us had 6 empty estate spaces. I played last, but placed my final ship on my last turn, so I was actually in first place on the turn order track when doing final scoring.
We decided I won (I was also the last player in the first turn of the game), but it didn't feel very definitive.