Can I gush about Gargoyle's Quest here?
Cool.
I never got to play this back when GB games were still being produced. In fact, my first experience with it was an impulse buy from the 3DS Virtual Console. All I knew was that it was a Ghosts 'n Goblins spinoff, and that the third game in the series is apparently pretty godlike.
So, keeping in mind when the game was produced, I started playing it, and after a laugh at the somewhat lol worthy localization, I was surprised at how... well, not janky the game felt. I mean, it's very obviously a Game Boy game from 1990, but it feels and plays a lot more mechanically sound than I would have thought. I loved it so much, I went and bought the physical cartridge (Which thankfully isn't expensive at all, at least if you just want the cartridge!) and beat the game again on that.
Anyone looking for a somewhat challenging (But nowhere near the level of G&G) platformer with some very light RPG elements (World Map, Random Battles...) should definitely check out Gargoyle's Quest.