Play Monster Maker 2 - Uru no Hiken (Japan) Online

Monster Maker 2: Uru no Hiken came out in 1999 for the Game Boy, developed by J-Wing. It was part of that late-era wave of Japanese RPGs that really leaned into niche, experimental ideas, especially on handhelds. You don't see many games like it, even now.

You play as a monster breeder who creates creatures by drawing their body parts on a grid. Your main goal is to explore dungeons, fight other monsters, and collect special items to improve your creations. The combat is turn-based, and your monster's performance depends entirely on how well you designed its anatomy and elemental affinities. The pacing is methodical; you'll spend a lot of time tweaking designs between battles. It feels like conducting a strange, personal experiment every time you enter a fight.