Am I the only person facing such a problem or registration is temporarily phased due to flooded sign up through signature campaign applicants ?
Should use another browser if that didn't helped, otherwise the problem is on their end. Have you tried registering again?
I only suspect that maybe your country of residence is being restricted by the platform. As I looked at the signature campaign rules and requirements, some countries are mentioned that they can't joined the signature campaigns. So I assume that is maybe the case that's why you can't registered, (but I maybe wrong!!!).
But I did enjoy the rocket game, got busted though..