Resurrecting this thread to bring you my first and favorite video game (maybe tied with Pokémon Yellow, but this one gets my "my first video game" bias).
Donkey Kong '94 (actually just "Donkey Kong," the '94 makes it easier to distinguish) is a 2d platformer/puzzle game from 1994 for the original GameBoy. It's actually one of the first games made for the Super GameBoy, an attachment for the NES, that gave the game an arcade style border and color palette that was more expansive than the original GameBoy's 4 colors (unfortunately Nintendo chose not to use the expanded color palette for the 3ds port of it
). You play as Mario, and the game starts with the first four levels of the classic arcade Donkey Kong, then proceeding 9 stages with 96 levels as you chase down Donkey Kong in order to save your love interest, Paulina. This game is my favorite because of a wonderful mix of creative levels, Mario's expansive moveset, and some
absolutely beautiful 8-bit music.
The game's mechanics are wonderful - some levels have tiles that let you build temporary bridges/ladders/trampolines/blocks, some have levers that control things like the direction of moving platforms or extendable bridges, some have ice walls that can only be melted by the classic fireball enemies, some have disintegrating floors, some have vines to climb up and down (or animals whose tails act as vines), and in some your hammer will break through blocks in your way. Mario's moveset includes backflips, using a handstand to deflect falling objects or jump higher than normal (or double jump if you're fast enough), and picking up/throwing enemies/objects. While he does have a problem with heights (falling from some heights will stun him, and greater heights will kill him), it makes the game more interesting by adding a hazard to be aware of.
You don't get a lot of the standard Mario themes (Mushroom Kingdom, Koopa Troopers, etc.), instead getting more generic stages (like Big City or Jungle). However, I don't really see that as a problem, since one of the biggest complaints about Mario these days is repetitiveness (though the saving-the-love-interest theme is still in this game). There are mushrooms in this game, though they shrink the player instead of make them larger (and are used in certain levels where you have to be small to proceed).