Dose the forum game genre matter? Or does it have to be a certain type?
It just has to be a forum game, no matter the complexity or simplicity of the game. As long as it's run in and/or takes place in the forums, it would go there.
Well, I break them into three categories myself.
Mindless posting games. (Vending machine)
Free-form Roleplaying. (Hall of Heroes)
Thought out and structured games. (Continent, Kill Dr. Lucky, Mafia, etc.)
I should probably break the third category down into 2 or more but that will do.
Anyway, If there is something you would like to do, my advice is just to do it. Be as creative as you want. If you put something up that we haven't done before, that's awesome.