If you could go back in time and fix one game.

[effilctar]

Well I don't know if I could fix this but make it so the parents of the little kids that play Halo 3 wouldn't allow them to.

go back in time and sterilise the parents, problem solved

 

[Joshimodo]

Find out who thought making the CoD series easier and..."stop" them.

 

[BolognaBaloney]

I'd go back in time and make Halo 3 actually GOOD.

Ok, well instead of creating flame-bait, would you care to elaborate, perhaps give some examples of what you would change?