Question: How do I play with friends?
Answer: To be able to compare your brain map and scores with your friends, you need to link your Facebook account to your Peak account: open Peak, tap on the 'Me' tab (then on 'View and edit profile' for iOS) then scroll down and tap on Peak Social.
If your Facebook friends have also activated the social feature in their app, then you will be able to compare your brain map with them and you will see their scores in the "Challenge" tab of any game that you play (as long as they scored higher than you!).