Mega Man X is easily my favorite 2-dimensional platformer ever.
First of all, the gameplay of Mega Man X was simply phenomenal, although it was it was difficult, it wasn't too hard that you'd give up playing. The bosses were what made the game hard, but at the same time, they were what made the game amazing. The classic X-blaster was always your weapon of choice, while you strove to acquire upgrades for your X-blaster, secondary weapons (helpful for bosses), health tank upgrades, sub tanks (for storing additional health), and other secrets.
The graphics and music for Mega Man X were some of the best of the 16-bit generation. The graphics and color of the game were nearly unmatched by other 16-bit games. The graphics were so masterful, that enemies in the game would respawn when your screen scrolled past their initial locations, because the SNES couldn't handle both.
Mega Man X is nothing short of a masterpiece and a classic. It is a game that will never lose its fun and replayability. Mega Man X is a 2-dimensional platformer that should never be forgotten.