Ori and the Blind Forest/Will of the Wisps - My absolute favorite platformer ever. Like playing a beautiful painting, with excellent music, and satisfyingly tight controls.

The Subnautica series - Great story with deep lore, but also has fun base building. Latest game has multiplayer up to 4 person co-op, but can also be enjoyed alone.

Stardew Valley - You mentioned this.....just get it. Seriously, I never met someone who didn't like it. Sorry for the 200+ hours of your life that are about to disappear. The very definition of "cozy game".

Dave the Diver - Fun and quirky game. "Base building" via a sushi restaurant, but also exploration and combat elements. There is a weeb character that makes your guns and your sushi chef is an eccentric man who is a bit too crazy about his sushi knives. New expansion DLC coming this summer.

Cult of the Lamb - Has co-op multiplayer local and remote. Base building meets rogue-like with cute animals that join a cult.

Lovers in a Dangerous Spacetime - Best played with up to 4 person local or online co-op. Weird name, great game.

Ratchet and Clank: Rift Apart - Rivet and Ratchet OTP

It Takes Two - Requires co-op, either local or online. Excellent game to play with a significant other or close friend.