英文翻譯：
After downloading the game, it cannot be uploaded. The file must be in ZIP format for it to work on the device.
Viewing post in In The Middle Of Ages (C64, Playdate) comments
Thanks for pointing that out, I just tested the sideload per simulator (where a pdx file is enough) and not via Playdate account, I should have read the documentation.
Now the Playdate version is a zip file (I just tested the sideload on my device) and it also contains a new version 1.0.1 which contains a small bugfix.