PainStation is essentially a version of Pong gone bad. Or good, depending on your outlook.
This sadist’s interpretation of Pong expands on its classic predecessor by adding real pain to the formula. Miss a ball while playing and you are instantly subjected to one of three physical penalties: heat, electric shock or whipping, with the punishment decided by which symbol the missed ball hits. Furthermore, this thing actually causes pain: see the picture below (or the gallery of injuries at the PainStation site) if you don’t believe it.
PainStation is the work of German artists Tilman Reiff and Volker Morawe, and is currently on display at the Computerspielemuseum in Berlin, as part of a huge games exhibition I really want to attend.
Also, this thing might be kind of old. Actually, it definitely is. It was built in 2001. Sorry about that, but I only just saw it, and wanted to share.