Round Go is played the surface of a disk. The disk has a hole in the center. Kind of like playing on the top side of a donut.
There is a round go pdf you can print out here:
Here it is: http://www.youdzone.com/go.html
"It was Harald Schwarz ( email@example.com) who introduced this form of go during the European Go Congress Summer 1996 at Abono Terme in Italy." from http://www.youdzone.com/go.html
See also UnusualGobans.