It can be "yours"
just have to wait
Why is "yours" in quotation marks? Something that isn't really yours?
you'll go through its doors
before discovering a grizzly fate
There are countless doors in the game but the word grizzly makes me think it's a 'bear' reference. Barret in the sailor suit?
many lives are created
some say you're playing god
This reminds me of those creatures infected with mako in Mt Nibel reactor.
some simply just plain old hate it
because the means are rather odd
A part of the game that people hate? Could be anything! The last line seems like a big clue though.

Putting all this together I think one thing is very clear. When you say Mt Nibel very fast it sounds like 'Mount Nipple'. The only mounts that have nipples I would guess belong to Tifa.

My answer: Tifa's breasts