So, rocketcrab opens games in iframes, so techincally I could have a mode where it would open four or so iframes on your screen to demo a game. The problem is that this would not work for many of the games as they rely on cookies/local storage that would be messed up with multiple iframes.

You could also just try opening rocketcrab as is in multiple tabs, but you'd run into the same issue with some games. Best you could do is open Chrome, Firefox, Safari/Edge, and your phone to get 4 players xD

Ultimately, my plan is to add screenshots of each game. Kind of like the App Store. I've been slacking on doing it for more games cause it's a lot of work, but here's an example:

https://rocketcrab.com/game/drawphone

Otherwise, developers are free to add their own demo mode (Drawphone has this!)