Caveman Games on NES. I had several friends who had this game, and I always wanted it just because it looked cool at the rental stores. I remembering playing it at their house and not really understanding how to play it properly, but still wanting it. Sure enough, many years later when I started picking up NES games as an adult, it was on my early list to grab.
Also, I knew ONE guy that had a 3DO while it was still an active system. He bought it right after the first round of price drops. It seemed awesome at the time. We always played Gex and PO'ed. I eventually got a PS1 instead, but I was super happy when I realized that a slightly better version of PO'ed was available for the PS1. I played the hell out of that game.