1. Reptile: The First Secret Character
Though Reptile has since been a playable character a million times over, his appearance in the original Mortal Kombat was surrounded with an air of mystery. By performing 2 flawless rounds and a fatality on the "Pit" stage, a player would be rewarded with a secret battle against the mystifying green ninja. Reptile's inclusion as a secret character would set the stage for unlockable characters in future fighting games. And though you've battled a lot of special bosses since then, no moment would be quite as exciting as the first time you exchanged fistacuffs with the lovable Sub-Zero palette swap. Ahhhh, murderous memories.
2. Street Fighter Invents Special Moves
Although the MK crew would hate to admit it, they can thank Street Fighter for their plethora of special attacks. Before Street Fighter, fighting games were primarily boxing and karate emulators. It was our old pal Ryu who introduced "throwing magic stuff while yelling" to the gaming masses. Street Fighter II would perfect the special moves introduced in the original and subsequent games in the series would innovate the way we dish out combo-based punishment to our enemies: Street Fighter or otherwise.
3. Marvel vs. Capcom Revolutionizes Cross-overs
Marvel vs. Capcom set the standard for all fighting game cross-over series. An arcade classic, the original "X-Men vs. Street Fighter" played like an 8-year-old's dream. Now your friends could finally stop arguing about who would win in a fight between Wolverine and Ryu The answer was at their freakishly pale gamer finger tips! Marvel vs. Capcom paved the way for Super Smash Bros. and practically any other fighting game that could be described as a "clusterfuck of awesome."