When did this button appear? I've just noticed it under the game I was playing.
Quote:
Select a Neofriend you would like to challenge, or enter their username into the text box.
Once you hit 'Send!' below, an event will be sent to your opponent. If they accept your challenge, an event will be sent to you. The next score you submit for that game will then go towards all accepted challenges. If your opponent declines your challenge, you will be notified and your challenge with them will be cancelled.
Do you win anything for this? A trophy?