A great game that is all but forgotten. This is what Kid Icarus should have been.

User Rating: 9.1 | Olympus no Tatakai: Ai no Densetsu NES
The other reviews do this game right so I'll just add that it's a great game that takes the setting of Kid Icarus, adds the maturity and complexity of Metroid, and makes a great action/adventure game with a hint of Adventures of Link.

Boss battles, exploration, items, power-ups. All the hallmark traits of a classic adventure title plus the setting of ancient Greek mythology. Brought to you by Broderbund, one of the best publishers on NES that brought us other great NES titles like The Gaurdian Legend, Legacy of the Wizard, Spelunker, and Deadly Towers. All were exceptional games that went by unnoticed compared to the Nintendo releases

It and its brethren would make a nice title on VC or a rare find for your old NES.