How about instead of just a League of Legends subforum, we could have an Online Games subforum.
Each thread in the forum could be tagged with the game the OP wants to discuss, say, something like this.
[League of Legends] Patch 76.4 WTF PINGU IS SO OP
OR
[RuneScape] Jesus Christ, I can't believe Jagex has been run by bots the entire time!