Which browser do you use? Are you using Safari by any chance?
Waterfox currently by default does not support a feature used by this game called pointer events. Because of this, clicking will do nothing. For now, you can either switch to another browser or manually enable pointer events support by visiting "about:config" and toggling the "dom.w3c_pointer_events.enabled" value to true.
The new version of the game I'm currently working on will have a workaround for this issue.