[weinzierl]

It's a speciality of the Tornado tables which are mostly used in the US. It was introduced as a cost saving measure, because four additional figures are cheaper than a curved playing surface.

The curved corners in a traditional table are of course necessary to avoid the ball being dead in the corners. With three players you don't need a curved corner and can still always get the ball.

Here is a video of the ITSF world cup, where you can see that there is just a single goalie on every side: https://m.youtube.com/watch?v=3vnrAIOWDwo&pp=ygUOaXRzZiB3b3J...

There is actually a quite interesting documentary out there which tells the rise and fall of foosball in the US which is tightly coupled with the company behind the Tornado tables if I remember correctly. I saw it on Youtube a while a ago, but could not find it now. Might have been "Foosballers" but I am nit sure.