15 minutes is too short. If you get a bye in a tournament this means you've got to remember to play a shot every 15 minutes and if you get distracted and forget you get DQ'd even though you'd be around if you heard the "boyng" sound.

If tournament rounds are 30 minutes then 30 minutes would be a better idle time. Either that or a new sound after 14 minutes of idle letting you know that you're about to be logged out.

Maybe when a user enters a tournament their idle time limit is lengthened.

would make sense

Good idea. I don't think it would work out having the time limit changed when you enter a tournament though, probably a bit too hard for Nick to code?

Very good idea though.