I've got so many but here's a few.
Darius Gaiden - Arcade, Saturn, PS1
Shmup. All the enemies are ships based on underwater animals. Music and atmosphere is awesome.
Dariusburst Chronicle Saviours - Arcade, PS4, Vita, Steam
Latest version in the series. Same awesome gameplay, music and atmosphere and heaps of content. Steam version has support for playing across 2 monitors in arcade mode.
Firemen 1 and 2 - SNES, PS1
It's pretty much what it looks like, you're a firemen and you go around putting out fires. It's an Ikari warriors type shooter with different types of fire or fire related enemies. It has a lot of charm and a full blow story with optional side missions. First game came out on SNES, second on PS1.
Panic Restaurant - NES
Platformer. Pretty easy but still a lot of fun.
Sheep, Dog N Wolf - PS1
Cool puzzle game where you play as Ralph and have to figure out how to sneak pass Sam and steel sheep. Some of the puzzles were really well designed and the graphics still look great.
The Adventures of Little Ralph - PS1
Awesome platformer. Still holds up today, tons of variety, great graphics and level design. It was only released in Japan and it's like $300 but it emulates fine.