I heard about this from a colleague, who played it as a kid, and then I saw it today on another colleague’s shelf, who promptly gave it to me as a gift (Thanks, Jack!). It is some kind of game with wff’s (in Polish notation), I haven’t looked at the instructions yet. I thought something this weird could not have survived on the market for long. But apparently you can still get it from www.wff-n-proof.com/ or used from Amazon etc. Does anyone still play this?