LogFAQs > #979343513

NES
Genesis
OG Xbox

I think these three systems will reasonably be hurt in credibility if you limit one game per franchise or series -- it's hard not to imagine two Mario/Sonic/Halo games for each of these. They were just so core to those system experiences.

I believe the PS1 has a similar but lesser risk with Final Fantasy getting multiple reps on the mountain. If you're going to test this kind of rule, maybe try it with the other systems I named first to see how that goes without the rule first...and if that starts to get weird, you can always add the rule here by then.

But I do think Metal Gear Solid, Castlevania: Symphony of the Night, Crash Bandicoot, and people's general tendencies not to flood their nominations with the same series/franchise (alongside FF7 being the overwhelming favorite for FF-rep this generation) will be enough to stunt this risk you're concerned about.