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Klonoa: Door to Phantomile is set in the fictional world of Phantomile. Environmental factors such as small, localized tornadoes and springboards launch Klonoa up or forward, allowing the player to overcome obstacles. If the player holds the jump button Klonoa floats in mid-air for a short duration by flapping his ears, which increases the jump length. From this position, he can throw the enemy into another enemy to defeat them, or use the enemy to perform a double-jump allowing for new locations to be reached. If the Wind Bullet hits an enemy, Klonoa lifts the enemy above his head. The player defeats enemies by utilizing Klonoa's weapon, the Wind Ring, a ring that fires a burst of wind called the Wind Bullet. At the end of some levels, the player must defeat a boss. The game is divided by levels called Visions, where the player progresses by following a path with defeatable computer-controlled enemies and puzzles that must be solved.
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This allows the path followed to curve and for the player to interact with objects outside of the path. The player moves the protagonist, Klonoa, along a path in a two-dimensional fashion, but the game's surroundings are rendered in three dimensions. Klonoa: Door to Phantomile is a side-scrolling Platform game viewed from a 2.5D perspective.
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