I've thought about this before, I personally feel it would be a good, small thing.

There's a buildup of players in free channel 1 mostly, but all channels including clan war, that are just lingering in the lobby taking up space. The 250 limit on the free channels is usually full at random times and it takes FOREVER to get back in because of all of the afk people and players that are playing. Then there's games that are created and people just go afk in the game room or they end a good game such as a Garden TDM because they go in the game to play, the AFK in the game, and when the game ends they usually are the room host next and no one can start the game. I think that a 10-15 minute AFK session OUTSIDE of an ongoing game (Lobby, Game Room, CW Channel, etc..) should result in the player being logged out and sent back to the login screen where they can properly AFK for hours and leave room in the game for players who actually want to play. They can log back in and return when they come back to the game. Also some players like having a lower room number like 1-8 on the first page to attract players because the higher numbered rooms don't get as much attention because the other games before it are being played more.