You'd probably have to export your sketch as a Java applet. Not that modern browsers support applets anymore.
Thank you,
but what is a java applet?
Processing 3.0 lets you export your sketches and builds this folders application.windows64 where you can find:
- Application that runs your sketc
- Lib folder with core.jar, sketch.jar, and other .jar files
- Source folder with your .pde processing files, and a sketch.java java file
What is the java applet and what do I have to upload to itch.io?
An applet is how you run Java apps in a browser. If you don't know what it is, and you didn't export your game as an applet (assuming Processing can do that), then the answer is none.
But again, modern web browsers don't support applets anymore because they were a big security issue. I recommend just letting people download your game.