Treasure Hunts are limited time events that take place in the Events tab of Two Dots. Each Treasure Hunt consists of 7 brand-new levels, a new map, and a custom Medallion. Completing all 7 levels before the time runs out will allow you to collect the Medallion and add it to your collection. If you lose a level you will lose a Heart and you will not be able to move to the next level until you retry and complete it. You can see all of the Medallions you've collected over the years in the Collection tab.
When you complete the Treasure Hunt, the Medallion will have a stamp on it that shows how you ranked among all Two Dots players worldwide for speed of completion. Treasure Hunts also have a leaderboard where you can compete against all of your Facebook friends for the best cumulative score.