Technology

It works by streaming the game and basically just manages shared input. However, you are correct, I should have said ONLINE multiplayer (and I'll edit that).

However, given this was a big thing a few years back, and the person I responded to "couldn't even think how that would work" says a lot imho. https://www.gamedeveloper.com/business/steam-s-biggest-feature-for-indie-devs-is-its-least-talked-about specifically

I'll also add, I'm playing a game similar to minesweeper at the moment (proverbs). Shared mouse/keyboard support would be good for some couples playing. There is no concept of multiplayer implemented, and yet, something like this could add very basic support quickly. Broken Age 2 I'm also playing, which is a point and click adventure game. I'd never play it multiplayer, but would also be cool to play with your girlfriend and you take control during different parts. Or, you can play games where there is simultaneous mouse / keyboard control normally. Instead of only 1 player doing both, you could split over the internet. Couch Co-op, even better, as both players are totally independent.

These are all applications which any "games dev" should certainly be able to think of immediately. Instead, it feels like, they just wanted to talk smack.