Of course the original creator sets the baseline, but there absolutely can be rules created past the original creation of the game. For example, my friends and I generally disallowed playing as Oddjob in Goldeneye back in the day. Totally valid within the context of the game programming, totally disallowed by social convention.

Ah yes, Oddjob. I take that as an example of accidental imbalance though, not deliberate game design. I seem to recall the developers even saying something like "yeah, we realized it was broken, but thought it was funny" (not a direct quote.

I guess my viewpoint assumes that gameplay is legitimately & deliberately balanced. I suppose this is much harder in videogames with game characters having different skill sets. It's much harder to evaluate whether or not there is balance between them than, say, Monopoly: Everyone starts the same there-- the dog isn't any better off than the thimble. (Though I usually play as the dog, and pretend the thimble is a fire hydrant as I pass it by & do what dogs do... I may not be very mature for my age. It makes my kids laugh though)