And done, 100% completion. Was sort of familiar, having seen others run it. Enjoyed it a great deal. The difficulty definitely gets ramped up in the last two worlds, but it feels like a good balance throughout.
If you want to check it out, there's a free demo! metagamemike.itch.io/kero-kero-co...
metagamemike.itch.io
A cartoony western platformer for the Game Boy Color & Analogue Pocket!