Startropics is a hidden gem? Forget the title of it but there was a guidebook I got way way back that had walkthroughs with full-color maps for a bunch of NES games and Startropics was one of them so I figured it was fairly well known. IIRC, the other games were the NES Mario and Zelda titles, the Castlevania games, Rescue Rangers and Ducktales and probably a few Mega Man titles too. Wish I still had the book for nostalgia value.
Have to say though, it pleased me greatly to see Crystalis as a recommended title. Ignore the mess the GBC made of the game and play the classic. My favorite NES title bar none.