The challenge mechanism is good as it is now. Maybe the challenge notification and the challenges panel could be moved to the Games section.
Mojko wrote:
...... However, note that if I remove this limitation someone can join 10 of your games you hosted for example. This can block your slots in some situations.
One solution for this, if easily done, is to raise the limit only for challenged games. So for example if X player hosts 5 games, Y player can only join one and if Y wants to play another concurrent game with X, he/she would have to send a challenge. Slots are counted as it is now, so if X have no free slots, Y cannot send a challenge.