Switch
On Switch you can get Yo-kai Watch 1 and 4, as well as Yo-kai Gakuen Y. (4 and Gakuen Y are also available on PS4) All of those games have furigana and mostly easier language. There’s sometimes higher level grammar and language when certain characters are talking though. It’s mostly just antiquated language for older themed Yo-kai.
Switch and Steam
There’s also Shin Chan: Me and the Professor on Summer Vacation, Shin Chan: Shiro and the Coal town (the sequel), and Natsu-Mon: 20th Century Summer Kid. These are all part of the Boku no Natsuyasumi franchise. The Shin Chan games both have furigana and easier language. I would say Natsu-mon is a little more difficult as it doesn’t have furigana or push to continue when some characters speak, so you may be a little lost in the beginning, but you can always replay the beginning of the game in english (if you buy the Steam version) just to make sure of your understand. I literally cannot recommend Natsu-mon enough. It’s one of my favorite games of all time.
Doraemon Story of Seasons : Friends of the Great Kingdom is very long, but I think the language level is great. On the Steam version you can choose japanese or english. I only played the demo in japanese, but have played the full game in english on the Switch. Wonderful game.
All of these are also lower stakes relaxing sort of games to play that will still give you a lot of reading practice.
Steam Only (I think)
The first Nekopara game is free on Steam. It’s a visual novel, so no furigana there, but you can always text hook it and use Yomitan to look up words. I actually haven’t played through this one in english or japanese, but it’s free and I’ve tested it with a text hooker before, so I thought I’d recommend it.
If you have a japanese 3DS or a DS then I can give you more recommendations.