Thanks for the kind words! I'm glad you're enjoying the game :)
Serenitrove is written in HTML and JavaScript. No PHP involved since the game runs entirely on the client side.
If you're trying to upload your HTML/JS game to itch.io, you'll need to include your index.html file along with any JavaScript, CSS and asset files your project uses. Put everything into a .zip archive and upload that to itch.io. The main HTML file needs to be named index.html for itch.io's browser-based hosting to work correctly.
Good luck with your project and thanks again for playing!