Steam's Summer Camp Sale is now in full swing, featuring daily discounts that are so good, you may end up buying another pile of games that you'll never play. The seasonal event is more than just a sale, however -- while the promotion lasts, players can complete in-game tasks to earn exclusive add-on content.

Each unlocked Summer Camp achievement earns Steam members a ticket. Three tickets can be exchanged for an item at the Prize Booth, which currently hosts unlockables like extra challenge levels for Dejobaan Games' AaAaAA!!! - A Reckless Disregard for Gravity, snorkels for the co-op bots in Portal 2, and the full version of Team17's shooter Alien Breed 2: Assault.

Many of the Summer Camp achievements are for popular games that you may have already purchased, possibly during previous Steam sales. Achievement-unlocking games are also conveniently discounted, if you don't yet own them. It's quite insidious! And a fun challenge, I guess. New activities will be added daily through July 10th.