Situation above, problem being the square with three builders around it. No legal way to finish everyone's aquaduct as is (no single curve tiles remained).
Green: No Master Builders in site for any meeple. Green moved a MB and then voluntarily declared his aquaduct in the mess above closed to take the podium space for points.
Blue: Also couldn't move, moved a MB and declared the one for the meeple on the right closed.
Green: Played normally for his remaining meeple.
Blue: Now was the last remaining meeple in the pic above. Played a straight to go over the square and get 2 extra VPs for an odd bit of aquaduct on the other side. Would have been illegal to join with either the left or the right aquaducts as they were previously owned by other meeples.
You played this right. At first I thought you played wrong and had to end all three aquaducts on greens turn. But because there was still a legal move to make by playing a straight you had to keep the aquaducts open.
You didn't break the game, it just sometimes happen that the meeples are manoeuvred into these positions. Perhaps by not having the right builders available and sometimes on purpose because the situation might give a few more points to a player.
What would have happened if there were no tiles left in the game that would have enabled any of the three meeples to legally place a tile? (not sure if that's possible)
One other question. Even though Green would never be able to legally place a tile in that space (due to no singe curves available), can he refuse to voluntarily close that aquaduct? I'm not sure it makes a difference, but if that had been Green's last meeple, would he HAVE to declare it closed?
I think you might be getting at this below where you mention that we may have been in a position where we had to end all three aquaducts on Green's turn... Do aquaducts have to be declared closed if there's no possible way for the next tile to be laid?
I reread the rules and I think I made one little error in my previous answer.
The section of the rules regarding closing off an aqueduct only state that you have to close an aqueduct when an adjoining tile does not extend an the aqueduct or when the aqueduct has reached the edge of the board.
The end game rules state: ..... the game ends with the player who laid the last tile. POINTS ARE STILL AWARDED FOR OPEN AQUEDUCTS, beginning with the player .....
I read this as follows:
The only time you MUST score an aqueduct is when it is closed by a tile or runs into the edge of the board. All others scores are voluntarily. So you are never forced to score an open aqueduct. But normally it is not wise to leave an aqueduct open which cannot be extended any further because the points, you can score for that aqueduct now, can and most probably will decrease over time.
So in this case it doesn't make sense for green to wait with scoring this aqueduct because waiting could mean that later in the game the points for his aqueduct are already taken by another player.
I hope I am making my self clear with all this talk.
Only reason I can think of to leave it open is if blue has multiple meeples remaining and green wants to take turns just moving a master builder without placing a tile, to try and mess up what blue is doing.
You move a master builder if you have none in sight of any meeples. Not quite sure if you can also do it if you have line of sight but no legal tile placement - we assumed this to be the case.