Metal Storm

This game came out really late for the NES era, to be specific in 1991. But I have to say that I am really impressed with the design, the physics are great and complex, the music is awesome, the graphics amazing. This is a NES jewel in every aspect. And even if you beat the game and you want more of it, they give you a password to try out the expert mode, which is really fun and insanely difficult.