We are happy you are enjoying it so far. Thanks for pushing through the technical issues and trying to download it again.
It is not your fault at all, we have not yet added a pause menu or an exit game button. You can never leave! Lol jokes! sorry about that :-P I know it's a pain to have to manually close the window. We will chat about if/when we could add one in to the prototype.
Hope you enjoy the future updates too!