There are several people who’ve requested multiplayer, which I also think would be a really cool thing to have, but I’d love for multiplayer to work as it did on Nintendo DS.
If multiple DS’s where in the same physical location, one player could start a LAN game which the other devices could join even if they didn’t have the game.
I believe the way this worked was that each game defined a LAN-subset of the game, which not every game did, which was small enough to be quickly transferred to other devices. Once the game sessions was over, the game would be deleted from the non-owning consoles.
I think this would be a really cool feature for playdate, even in a completely online setting.
It would be completely optional to implement, and it would make it much easier to play games with your playdate-equiped friends. I even think it would be a good marketing trick, with the shared multiplayer acting as a sort of demo for the game proper.
If memory serves, DS Download Play was done with a specific OEM application launched from the home menu. It would simply wait for a valid connection from another device providing download data, then execute the received data as an application that often would connect back to the providing device for multiplayer but did not allow subsequent reconnections without downloading again. Often, the multiplayer mode shared in this way was limited compared with multiplayer modes offered when all players had their own copy. I think sometimes the downloaded data was actually just a demo version of a single player mode, too.
It seems viable for the Playdate to do something similar… though I have no idea whether there would be any patent issues.
The Game Boy Advance also implemented this kind of functionality. If the device was powered on with no cartridge inserted (or if the user paused loading of an inserted cartridge on the startup screen by pressing Select+Start), it would standby to load an application from the Game Link port (connection with another Game Boy Advance or GameCube). It wasn’t only used for multiplayer or game sharing– it could also enable alternate game modes (The Legend of Zelda: Four Swords Adventures), feature-specific mini-games (Sonic Adventure 2: Battle’s Chao Garden), or just use of the Game Boy Advance as a controller for something else (Game Boy Player).
It does feel like the sort of thing Playdate developers would love to mess around with. Personally, I would definitely give it a try if I knew there was a standard way to implement this and with known file size constraints, etc.