Interlock is a fascinating puzzle set which requires players to connect blocks to create 3D shapes. Each 1 x 1 x 2 block has one plug and one socket in a unique location. You build shapes by fitting each plug into a socket of the next piece. When a puzzle is solved, each plug will fill a socket, and the completed shape will have no plugs or sockets visible. There are 50 shapes to build ranging from easy to hard. So what are you waiting for? Pick a block and start plugging!