I wish there was a mobile version of this game.
Don't install JoiPlay from Google Play, if the app is still even available. https://www.patreon.com/joiplay will have public links to the latest released versions of the app and the ren'py plugin. This solution only works with the PC version of the game, not the Mac version.
Other resources
In general, the JoiPlay Patreon will have the most updated versions of the app and the renpy plugin that may help: https://www.patreon.com/joiplay/about The JoiPlay Discord has some helpful experts who may help if you have other issues: https://discord.gg/vSguWn7tUJ
Known Good Versions - April 2025
JoiPlay 1.20.590 https://joiplay.net/repo/joiplay/1.20.590.apk Ren'Py 8.2.3 Plugin 1.00.70 https://joiplay.net/repo/renpy8.2.3/1.00.70.apk You CANNOT use the Ren'Py 8.3.7 plugin to play v0.16 of The Headmaster, it will crash the game on launch. You can install both plugins on your device and Joiplay will pick the right one, but if you only have the 8.3 plugin, it will fail.
Step by Step Device install
If you've never installed Joiplay before, this doc may help https://mega.nz/folder/mRJwGCyY#Gq1Tr8aqTTc8eiFY6R4szQ/file/zUAWxToT