I suppose they do, but that doesn't mean they should. Those examples aren't really like TU though. Gmod, TF2, CSS are community ran, and as far as I know, there are no rules other than server specific ones, which do pop-up on dedicated ones.
League of Legends makes sense to expect players to visit their website when the only way to get the game is... through their website. If I recall correctly, the game launcher also has (or had) community guidelines on it.
I can't really say anything about the other 3 though, haven't played them