There were two rental places within 8 miles of my home as a kid, so I didn't own very many games, but I played damn near everything (both of them had the Tengen unauthorized version of Tetris). I went to the one that would rent 4 NES (later add SNES, Genesis, Jaguar, and PS1 to that list) every weekend. Sad that place burned down. That it was in a college town and also the local liquor store didn't help the games odds of surviving that fire.
The net result is that I've played 90 out of the hundred most rare NES games according to that site. Also, *really* shocked that Dragon Warrior II-IV are all more rare than Princess Tomato in the Salad Kingdom (which was a comparatively lighthearted game in the lines of Shadowgate or Deja Vu playstyle-wise).
Played about half of the top hundred for SNES. About a quarter of it for PS1.
I'm actually surprised that most of my favorite games rate over 70%.
Didn't really start collecting until PS2, aside from a handful of GB games. I'll look at my collection of PS2 and later stuff this evening, I'm sure something like .Hack//Sign has to be pretty high up, given how impossible the later games are to find, and I have a complete set. Or Rule of Rose.