It's amazing how many games are actually obscure. Sega non main games generally sold in the hundreds of thousands only. So I love Phantasy Star, but it's forgotten.

Gunslinger Stratos for the arcade has a strong fan base in Seattle, and no where else. That game is awesome. It's a character death match game with controllers that change how you're attacking based on how they're being held. The same people made a magic school deathmatch game where you moved your hand to send out spells. ByKing and Squaresoft made some killer games.

Card and character based battle RPGs for arcades. Awesome stuff, sold terribly in the US.

Arcade Racing games that need a save card to fully enjoy. Midnight Club is the more famous one.

Virtual On for the arcade. Strong fan base, but nothing outside of it. They still sell the controllers for modern consoles.

Konami Wai Wai World. Konami man must save the various characters in the Konami universe.

The guy who wrote for Leisure Suit Larry also made a children's game about walking around a farm. You can play it on the Internet library.

The chess with fantasy characters game. It's like a chess board, but you set your pieces down based on what you want. It's an incredibly complex game with tons of strategy against an opponent. I had a roommate who loved that game.