Definitive?
in my opinion, going strictly on MVS, and the arcade scene
Samurai Shodown II
Samurai Shodown received a warm reception with its crisp gameplay and beautiful sprite artwork. It was no surprise that when Samurai Shodown II came out, the crowds grew exponentially. The game was simply ahead of its time. And while so many games have aged badly, Samurai Shodown II is still a sight for sore eyes. It has aged like Sean Connery.
Baseball Stars 2
This is the only baseball game that makes baseball look fun. Seriously speaking, baseball is a joke. But Baseball Stars 2 is awesome. Simple gameplay, lush colors, crisp art, and very competitive.
Metal Slug
Before the aliens, pirates, mummies and zombies, there were two soldiers versus an army, firing guns, tossing grenades, while new wave jazz played in the background. The presentation was tight. Later Metal Slug games completely lost touch with this. But the first Metal Slug was perfect.
Ninja Master's
Still one of the most underrated games in the neogeo library. There are probably still special moves derived from combos yet undocumented. Great backgrounds, great soundtrack, great character design, great controls. Overall, one of the best games on the system.
Last Blade
The only negative was that it didn't have the same excellent roster of Last Blade 2. Otherwise, the first Last Blade was superior in terms of backgrounds. From the snowfall effects to the fight on the ship. I also preferred Shikyoh for his desperation move in the first Last Blade.
Last Resort
It was a beautiful game back when it was released, and while it may not be as flashy as what has since been released, the soundtrack is still leaps and bounds ahead of its time.
King of Fighters '95
King of Fighters '95 was a break out game for the Neo Geo. It definitely helped that it was one of the first desireable neo geo games to get a proper port to another system (Saturn). I think this in turn helped make the game more competitive. I would play against people at Chinatown Fair who would go home and then practice on their Saturns and come back to play again. This was the last KoF that you had to really think in. From KoF '96, onwards, moves became intuitive. No crazy Desperation Move motions to figure out. KoF '95 is still on of the most challenging 1P fighting games, with good controls (sorry fatal fury special), to this date.
Nam 1975
When it came out, Nam 1975 was badass. It pretty much defined the Neo Geo. It's still hard as balls.
SNK vs. Capcom Chaos
It's not a perfect game, but it's one of the most beautiful games on the system, and the level of detail that went into making the game is stunning. Dmitri's Midnight Bliss is hands down the coolest thing to happen in a fighting game, deftly surpassing Kouryu's SDM in LB2. Anyone who wants to talk about how broken the game is can go back to their CVS2. I don't care. SVCC was a masterpiece.
Samurai Shodown III
Speaking of broken masterpieces, Samurai Shodown III has been the most maligned masterpiece in the SNK library. There are games that deserve to get trashed, but not Samurai Shodown III. Why does it get a bad reputation? Because in this swordfight, you can die within two hits. People want their sword fights to last longer. Take a second and think about the genius in that. Samurai Shodown III is possibly the most beautiful Samurai Shodown game to date. The spites they made in III would be carried on for generation it would seem, but the palettes would never be as good. Moreover, the backgrounds wouldn't be as good later on. The music after SSIII not as good. And it brings to mind the story by Pablo Neruda of the Irish king that commissions the court poet to compose a poem that would put them in history as Homer did for Ulysses. The poet spent a year and returned to the king's court with a brilliant poem, perfect scansion, meter, verse, everything was presented beautifully (SSII). The king and his court were floored at the beauty of the poem. The king rewarded the poet with a silver mirror and commissioned him to write another. A year passed and the poet returned with a new poem, but the verse was more rough, yet more visceral, and the level of detail was breathtaking. It detailed battles as battles were (SSIII). The king and his court were taken by the poem, but instead of having the poem taught in all the schools, the king locked the poem in an ivory chest, and commissioned the poet to compose one more. A year passed and the king asked for the poem, and the poet didn't want to share it. Upon pressure from the king, the poet delivered a single line of verse. And the king understood. Once true beauty is witnessed, anything less becomes more repulsive than before. The king gave the poet his dagger. The poet committed suicide, and the King became a beggar in his own land. That is the story of SSIII, and why it is so great.
