Treasure Key

Treasure Key is a tool item that can be redeemed for an unlocked Treasure. Previously, Treasures were locked and required Treasure Keys to open. All Treasure Keys will expire on July 1, 2015.

Removed Keys
(mods, i hope you can get do a better formatting than mine, changing wiki for 1st time)

Bug(?): not all keys were removed from the game. Some of them are still on some backpacks and Steam Community Market, and ARE NOT removed while being ingame.

Example: TI2012 key, Frostivus key, TI2013 key, could be more.