Pokémon light platinum is a Pokémon Ruby rom hack. You can find more information about it here: http://wesleyfg.weebly.com/pokeacutemonlightplatinum.html
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https://www.youtube.com/watch?v=Z8k52zVgPUQ
the first half of this massively massive castle.
for those of you who wish to play as well: http://www.smwcentral.net/?p=showhack&id=2318
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https://www.youtube.com/watch?v=dFGIJClYNPE