I really gotta get around to playing Destiny of an Emporer

I uhh, dont think very many of those are rare to be honest, especially the N64 games ^^. Just about every game you mentioned had large releases, they're just old now that's all. Except Pokemon Crystal, I'd say that ones rare, as I'm not even sure if that was an actual release?(Could have sworn that was a Hack by one of the more well-known pokemon hackers).

It's actually not too bad, but pretty simple. I never finished it though, because on two separate playthroughs I got really far, and then completely stuck. I'm convinced it was a glitch because the game just refused to tell me how to progress.
(This was before the internet had video game guides.)

I still have Unlimited Saga, and I love it.

I think the most rare game I have is Little Samson for the NES.

Mr Mosquito. It's not a rare game but....well, just look.

https://www.youtube.com/watch?v=CZpzlNUH_Hc