Here’s a helpful, informative write-up on Unity plugins for JoiPlay — aimed at mobile gamers who want to play Ren’Py or Unity-based PC games on Android.
Cause: The game is built with IL2CPP and Mono stripped out.
Fix: This is often fatal. However, try downloading the "Mono Unity Player" plugin (a separate experimental build) and select "Mono" instead of "IL2CPP" in the game's plugin settings.
The JoiPlay Unity Plugin is a separate APK you install alongside the main JoiPlay app. It adds the ability to load Unity games (usually Windows or Linux builds) on Android. Without this plugin, JoiPlay will show an error when you try to open a Unity game.
While the game is open, use the JoiPlay overlay (swipe from the left edge).
Space to Volume Up for skipping dialogue.