About

The Topspin puzzle is by Binary Arts (now called ThinkFun), but is also sold as No. Crunch under their XEX brand name. It consists of 20 numbered round pieces in one long looped track. You can slide all the pieces of the loop along. There is also a turntable in the loop which can rotate any four adjacent pieces so that they will be in reverse order. This in effect swaps two adjacent pieces and the two pieces on either side of them. The aim is of course to place the pieces in numerical order. It was invented by Ferdinand Lammertink, and patented on 3 Oct 1989, US 4,871,173. If your browser supports JavaScript, then you can play Topspin by clicking the link below: