By the looks of the choices here I am the first to reply under 40
Mortal Kombat - I was already hooked into SFII when this came out, but made my way over not long after. I remember resisting it thinking I was a SF loyalist. I got real good real quick. At the arcade it got to the point no one would play me, I had to offer to play people 1 handed. I haven't lost a game in about 18 years...granted not a ton of competition in the last 17 years or so. I could at its height play this game for 2+ hours on one credit (50 cents back then). The fighers looked real, outside of the jump kicks and spcial moves the movement was realistic, the game was a total chess match, reaction and counter, no move spamming here you paid for it.
SFIICE - The ability to take Sagat made this game amazing! The game that led an arcade resurgence.
Point Blank - This was in the Student Union in college for me, I would play this game everyday. It was on a showcase cab, and man I loved it. The recoil of the guns, the interesting challenges. I think I had every high score available.
Wrestlefest - A game that I always searched for in any arcade I walked into. I had so much fun playing this game, I would mercilessly beat on the opponents sometimes until the time expired trying to discover new ways to deliver moves.
Goal! - An odd choice but, friends and I played this and had such a blast. I used to take Colombia all the time and we used to give names to the players on the game and when we would score golas would shout the made up names. I spent so much money on this game.
Honorable mention - Primal Rage, NBA Jam, Tempest, Crystal Castles, Spy Hunter