Actually the first home version was licensed and designed by Coleco for the ColecoVision. They had rights to port to home consoles at the time prior to the NES in the US. I do have to say that I have played both the ColecoVision and the NES version and I can't tell a difference. Even that little spot on the 1st screen on the ladder where you can pause and then hurry up the ladder are in both versions.