For the cover, looks like NEC had an art competition in some middle school where the winners artwork would be featured in video game called Dungeon Explorer. Artwork is good for what it is, but it's by no means a professional execution which is required in video gaming industry. I agree with Bithead that this is one of the worst cover video game art in the world, but only based on the expectations from what is considered professional piece or not.
........you can skip reading the paragraph if you want. The artwork is shit.