It's not really a forum but I like going to
www.fanfiction.net which, as you may have guessed, is a fanfiction site, basically they have loads of catagories, games, films, animes and so on and each topic has loads of there spacific things for you to write fanfiction and review other peoples, they have a small Oddworld section, and for some reason, a pong section! Yup, I thought that to!
Only posted to stories there myself, prefer this place really. but I do know that I'm not the only Oddworld forums member there, just ask Kesiah!