FlashBack - Amiga (because it exist and I kinda know one of it's maker. It's beautiful, the story is awesome, the music too, …)
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(Another World is quite nice too, but for me it always looked more like a QTE than a platformer)
Zool - Amiga (it's an ad for Chupa Chups, but I loved it)
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Ristar - MD/Genesis (awesome, but pretty hard)
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Kirby - NES (this game really pushes the NES hardware to it's limits)
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Donkey Kong Country series - SNES (those games have something that pushes me to start a new game - again)
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Not a "real" platformer, but the first "metroidvania"
Castlevania SotN - PS1 (my favorite game of all time, spent many many hours on it and I still play it from time to time.). In fact, I would say that all the Castlevania series are nice games with some awesome gems like SotN, Rondo of Blood, Super Castlevania 4, Dawn of Sorrow, … (the 3D episodes NEVER HAPPENED!)
Do we have a Spelunky port on pandora?