The April 1st social experiment on Reddit turned out nice this year. Users were enabled to draw on the huge canvas, one pixel per 5 minutes for 72 hours. It resulted in a great example of co-creation.
r/place is a collaborative canvas on which a single user could only place a single tile every five minutes. This limitation de-emphasized the importance of the individual and necessitated the collaboration of many users in order to achieve complex creations. Each tile placed was relayed to observers in real-time.
Great detailed description of the project architecture is provided by Reddit on their blog. Absolutely fascinating reading, at peak times 80,000 users were at r/place simultaneously placing tiles. Some users chose to cooperate in creating the art and later, bots were created to draw automatically on the canvas.
! Heavy animations below.