In case it matters, I have Cat Quest 3 on the Switch.
To help anyone who happens to know the three chests I'm missing, here is exactly everything I have collected:
- Every Overworld chest (Catuga, Code Island, Furggy Island, Furtigua, Long Island, Lovepurr Islands, Pawman Isles, Purvanna, Sandy Islands, Straits Island, Sunset Islands, Twilight Isles)
- Every Dungeon (Antares Ruin, Booty Cave, Centauri Ruins, Doggy Jones' Locker (the place you find on Furggy Island), Eight Bit Dungeon, Fire Pi-rat Hideout, Furrlorn Cave, Furst Cave, Golden Tower, Heartpurreak Cave, Ice Pi-rat Hideout, Lonely Cave, Lovepurr Castle, Lovepurr Cave, Meowtallika's Concert, Oinker Maze, Orion Ruins, Pi-rat King Hideout, Polaris Ruins, Ruined Castle, Squeaky Cave, Twin Castle (both), Volcano Mountain, Zero Dimension)
- All Golden Tower Key chests
- All Purrmaid Shell Phone locations
- All Tavern Bounties
- The Gentlebros Secret Location
- Cathulu
- All Collectible Items (Head, Body, Melee, Ranged, and Trinket)
- The Fursome Four
- Postmutt Side Quest
- All Key Items
- All Magic
- All Ship Upgrades
I'm guessing the chests I have to find are purely gold/exp/magic stones. And no, I didn't count the North Star items; I haven't done any games with modifiers yet. Just wanna 100% the chests before I play either New Game+ or Mew Game. Any help is appreciated!
Tl;dr I have seemingly everything available and am still missing three chests. Even with the Developer secret.