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The K-O-N-G Letters (also formatted as KONG Letters or K O N G Letters) are common collectable items in the Donkey Kong franchise. In most of their appearances, they resemble flat, gold-lined objects with either of the K, O, N and G letters stamped on them. They are found in every level of the games, except boss battles. Some are out in the open, and some are hidden through the stage or in Bonus Areas. Their main function is granting an extra life to the player once all four are collected in a level, which is seen in the first three Donkey Kong Country games, Donkey Kong Land 2, Donkey Kong Land III and DK: Jungle Climber.
In Donkey Kong Land, K-O-N-G Letters play a completely different role. They must be collected to save game progress. If the heroes are to miss any letters, they will be unable to save their progress. The level Kong Krazy in the game has multiple sets of K-O-N-G Letters in it; in this level the K-O-N-G Letters can be used as platforms and bridges.
Their role was changed once again in Donkey Kong Country Returns and Donkey Kong Country Returns 3D. In these games, collecting all K-O-N-G Letters in one world unlocks a Key Temple stage, which conceals one of the magical orbs that are required to enter the Golden Temple. While playing the game in Mirror Mode, the letters on the K-O-N-G Letters are flipped as they would appear in a mirror. In this game, K-O-N-G Letters were redesigned to appear more simplistic, resembling plain orange panels with yellow letters.
In Donkey Kong Country: Tropical Freeze, they serve the same function as in its predecessor, unlocking a temple level once all of them are collected in a world. Each temple now holds a relic required to unlock the Secret Seclusion. Even though the K-O-N-G Letters retain the same orange coloration as in Donkey Kong Country Returns during normal gameplay, they are blue when playing in Hard Mode.