I might want to add a user as a contributor to the game, but not allow them to make changes to the game page, game price, delete admins, moderate the community, ...

I think all of these should be separate options?

Taking a look at what you ask I'd say the contributors should have specific groups then, so you can turn on allowing stuff, like:

Maybe a bit more expanded than this, but to get the basic idea, eh?

(And why can't I add text AFTER the table?)