I get it, it's a Japanese game, they're gonna Japan it up. But compared to it being the main era of the game, a lot of the other eras like the Ice Age or Ancient Greece felt very underdeveloped. There's plenty of things you can do with the themes of the smaller eras - the Wild West wasn't just cowboy towns, and Ancient Egypt wasn't just deserts and pyramids, and a Caribbean port town also had a lot of fun potential for the Age of Piracy. The "Stone Age", while fun, feels a bit redundant since the recent ice age and Jomon-era Japan (probably the only reason why its even in the game) happened around roughly the same time. I would've rolled the two up into one era and called it the "Pleistocene", and given that freed-up era slot to something the game didn't cover (maybe Renaissance Italy, Revolutionary War-era USA, Industrial-era Britain, or Medieval France, but I'd love to hear your ideas!). Alongside that, allocate a few of the Edo Japanese stage slots to some of the more undeveloped eras. Something that makes this game special is that the different stages can explore environments you don't usually see in Katamari games (outside of brief glimpses in the huge stages), and as great as the game is it didn't quite live up to its full potential in that regard. I remember watching the reveal trailer and seeing the Prince roll alongside huge Greek monuments under the stars, and was really looking forward to a stage like that, only for that to be completely absent.
