Despite sharing a name, this isn't a Game Boy Color version of its more famous PS1 cousin. It's actually a non-canonical sequel to the original Metal Gear where Solid Snake is dragged out of his cozy Alaskan retirement to once again stop a Metal Gear from running amok at Outer Heaven. There's no Shadow Moses Island here, although some familiar MGS personnel do appear, like Colonel Campbell and Mei Ling. While playing much like the original Metal Gear titles, this game does have some improvements over those. For one, the animations are really great in this. Snake has buttery smooth animations, and the enemies have a large number of turning and looking around animations that expertly convey their intentions, even when their faces are literally a single pixel. In typical Metal Gear fashion, it also does a good job incorporating the items you find into your environments, such as using boxes to hide and solve puzzles, equipment to see in the dark, and an arsenal of weaponry to utilize. Also in typical Metal Gear fashion, this game manages to pack in a detailed narrative featuring quite a bit of dialogue about the nature of war, global conspiracies for world power, and just some awkward conversations about love and revenge. There is quite a lot of content here, and I think it's safe to say that this is easily one of the best games on the Game Boy. The levels do become a bit labyrinthine at times, and the final boss is a horrible spike in difficulty, but aside from that, it's a really well made and well crafted entry to the series. Strange how it was non-canonical even when it was released though, I suppose it's Japanese title of Metal Gear: Ghost Babel really would've fit better.

For a GAME BOY COLOR GAME, this honestly cooks. The gameplay has so many mechanics from Metal Gear Solid (the other one, on ps1) thrown in that it can feel a bit like Link's Awakening and feels awkward. It's also pretty hard to get used to. But everything else, wow. The story just gets better and better throughout the game, and unexpectedly ends up a very cool spinoff/alternate reality to Metal Gear 2: Solid Snake. The game looks GREAT (though I can't imagine it being very....visible on an actual Game Boy Color). Snake's animations especially look great, and the cutscenes are well.
The music, while consisting of a lot of music from Metal Gear 2, sounds good and the remixes are about as good as the original (with some, like the Encounter theme, I think it sounds better).
oh also the final boss was kinda annoying yeah