Sorry, since this is an HTML5 game played in the browser I don't think itch.io will let me have an option for people to download it, unfortunately. :<
EDIT: If you're using itch.io on the browser, you should be able to run it right in the window. If you're using the itch.io client, you need to either click the launch/install option or you need to move to playing in a web browser if the option isn't there.