I'm glad you're enjoying it! I think it could easily expand to three or more players. Character creation would go the same and then after Player 1 resolves a prompt, the other players can both have a turn having their characters respond or react to what the first player wrote before Player 2 plays their own card. Then Players 1 and 3+ can have their characters react/respond to Player 2's answer to their prompt before handing it over to the third player.

If at any point in the scene it makes sense that only two of the characters are involved in a prompt or series of prompts, you can have those two players pass the document between themselves until it makes sense for the third player to jump in as well.  You can easily add or remove players as necessary. But for the most part, because it's a game about reacting to what the previous player did, I think you could easily play with as many people as you want. Just make sure everyone is on the same page wrt safety and consent.