There's another aspect of GRIS that I think warrants mentioning, which is how -intuitive- the gameplay is, despite the lack of tutorialization (besides the button prompts when you first gain an ability). It really is remarkable, though the relatively simple controls and puzzles certainly help with this. The world's design manages to perfectly signal to the player whether an object is interactable without breaking immersion, and the way collision is handled is inspired as well. I don't know whether these lessons would be directly applicable to your games, but I think just appreciating them can help expand one's mind when thinking about how to implement game mechanics.

Another minimalistic platformer that does this well is Inside, which has even more simplified controls, though puzzles/obstacles are often solved through trial and error rather than being strictly intuitive. Nevertheless, the game feels like one continuous shot, which I hear is a favorite among film buffs as it helps greatly with immersion and is no easy technical feat. It always fascinates me when a game can be an enjoyable experience without any UI to speak of- something about it feels so much "cleaner", though obviously that can't work for all genres (certainly not RPGs).