We agree to finish the game, BUT... our main complaint isn't that he abruptly left (things happen, especially with a valid reason), but that he experiences crashes every turn, and he can't save, so he has to redo the entire turn, which means we have to wait (and playing with 4 people already takes a lot of time). As I understand it, the HD mod allows saving, although maybe I'm wrong.
Anyway, let us know, and we'll try to finish it. We don't need a technical win, but we also don't want to waste a lot of time again. Maybe he can fix something, adjust the settings, or do something else to prevent this from happening again, and then we can finish the game.