This could be fun on nostr. Create a not with a webxdc app (a self contained app that cannot access internet). All it can do is send messages to other participants (in nostr, it could be a reply to the main note).
Very simple tech and you magically have things from polls through simple games to a collaborative editor without the need to implement new note kinds in all clients.
Furthermore, by leveraging the open source implementations (such as DeltaChat's) for all platforms (desktop, ios, android), it is easy to implement it. Just implement one send function and one receive callback and go.
It's offline/async ready.
I recommend people play with this in DeltaChat, it's quite fun.