What are the main best sites for cheat codes
There's gamefaq, there's ign, and you can basically just google it and it will show you some available sites... But I don't usually use cheat its just a spoiler I only do it if I finished the game and there's nothing to do :) but its up to you :)
Why cheat and finish the game
Google it. Or, watch a walk through on Youtube or something.
Ign, cheat code central that's all I use