Donkey Kong by Nintendo for their GameBoy, released in 1994.
Here's an anomaly for you! Released quite late into the original GameBoy's life, DKGB was designed to take advantage of a new peripheral for the SNES, dubbed the "Super GameBoy" - a device that would play the entire library of original black-and-white GameBoy games and pipe them through your SNES onto the television.
This cartridge in particular would display in a special "limited-color mode" when played in such a fashion. Mind you, this all preceded the GameBoy Color, which was not compatible as one would hope.
The game itself was a spin on the very classic original Donkey Kong formula, aping the original game (I'm so sorry) for the first few levels before launching into the true meat of this quest.
Eschewing the whole Mushroom Kingdom canon altogether, this game presented an entirely different take on the whole story which harkens back to Mario's original "Jumpan - rescue Pauline" roots and is quite refreshing for it.
Sadly, the game was a true undiscovered gem. Branding the game as simply "Donkey Kong" and starting the game off as a throwback to the original, it looked like the game was simply a port of that much older original game. Those who knew better and played the game were in for quite a feast of a game, among the best the GameBoy would ever offer.
After dispatching the homage to the original levels, the gamer would find a huge and complicated platform/puzzler hidden within, as each "screen" challenged our famous protagonist to seek a key and exit to the next levels.
Each world ended with a boss battle, and a longer journey followed through several of the same, all with different themes (Jungle, Pirate Ship, Airplane, The Big City, etc) Mario's moveset was hugely expanded upon, and the game really shines in it's design and execution.
The game can easily be seen as a precursor for the ensuing GBA and DS games such as "Mario vs Donkey Kong" and "March of the Minis,' but in no way is it inferior to any of those titles gameplay-wise.
Despite the very dated tech, this game still tops many GameBoy fanatics' must-have lists and is extremely fun to play through today. An overlooked classic worth anybody's time!
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