You more than likely won't be allowed to play anywhere at 15. And often, even 16 isn't allowed in Ontario unless a parent is actually playing in the game as well. Exceptions are sometimes made in private games and 16+ are allowed, but don't count on it.
If you become an active member of this community and prove yourself mature, you may be allowed to play in private games before you're 18. But again, don't count on it.