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K-O-N-G Letters (also formatted as KONG Letters or K O N G Letters), also known as Golden Letters, are common collectable items in the Donkey Kong franchise. They are a set of four items that can be collected in a level to obtain extra features, most commonly extra lives.
Donkey Kong Country series
In their original appearances, KONG letters 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.
Their role was changed in Donkey Kong Country Returns and Donkey Kong Country Returns 3D. They were redesigned to appear more simplistic, resembling plain orange panels with yellow letters. In these games, collecting all KONG Letters in one world unlocks a Key Temple stage, which conceals one of the magical orbs that are required to enter the Golden Temple, thus contributing to the game's 200% completion. When all letters are collected in a level, the game acknowledges it by adding an orange pin with a black star under the name of the level. While playing the game in Mirror Mode, the letters on the KONG Letters are flipped as they would appear in a mirror. Collecting them again in this mode does not contribute to the game's completion, but the orange pin will be replaced by a blue one for each level where this is done.
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. They have the same design introduced in Donkey Kong Country Returns in normal gameplay, but become blue when playing in Hard Mode.
Donkey Kong Land series
In Donkey Kong Land, KONG Letters play a completely different role, where they must be collected to save game progress. If the players miss any letters in a level, they will be unable to save their progress up to that point. The level Kong Krazy contains multiple sets of KONG Letters; after a set is collected, a button must be pressed in order to form all currently collected letters into a bridge that helps the Kongs cross a gap. Such buttons are always encountered shortly after the end of each set.
DK: Jungle Climber