Final Fantasy Mystic Quest is the "RPG for dummies", a simple Japanese RPG designed for western audiences.

The soundtrack contains some rock/metal-like bangers, which has made it a good source for video game covers like this one: "Boss Battle" by Daniel Tidwell. Another nice one: "Battle Theme" by Ferdk

There's a clear theme that's reused for towns and dungeons, in various speeds/moods. I picked the most energetic one for the music list, "City of Fire ~ Faeria".

"Last Castle" is probably the best track of the game, here's a metal cover of it by Dann Link.