When I was a kid, sometimes friends would hang out at someone's house, and one person would play a single-player video game, and the others would watch, comment, offer advice, and generally hang out. Even though it was a single-player experience, with eyes glued on screen, it was "social".

More recently, I saw a group of friends set up, with couches outside the tracking area, and watch each other taking turns at Job Simulator, Accounting VR, or Space Pirate trainer. They just had fun watching, socializing, and taking their turn. Panopticon and Keep Talking and Nobody Explodes also offer interesting, asymmetric gameplay.