Terraria, Risk of Rain 2, Hades.

Honestly I don't know many rated E games that aren't already listed, but if he's good with a bit of difficulty then those last 2 should be alright for him.

Also, depending on the sort of shows and movies you let him watch, God of War can be alright with proper supervision

EDIT: OH! Stardew Valley and Harvest Moon are great ones!