Castelian on the Game Boy is one of those weird little puzzle-action hybrids that somehow just works. You control this little ship thing (looks more like a Tetris block with eyes) bouncing around maze-like levels, blasting enemies and collecting keys to unlock doors. The first few screens feel simple, but then the layouts get seriously devious—walls shift, enemies respawn, and suddenly you're backtracking like crazy.

What I love is how it mixes reflexes with planning. You can't just rush in; some enemies take multiple hits, and running out of ammo means awkwardly dodging until you find more. The chiptune soundtrack has this weirdly catchy, slightly ominous vibe that sticks with you. It's not flashy, but there's something satisfying about clearing a screen and hearing that little victory jingle.

Fair warning: the later stages get brutal. I still haven't beaten it without save states. If you dig old-school games that punish impatience, this one's a hidden gem.