Also thought it was a joke. Absolutely not signing in to google for an unknown app meant as a novelty, and I can’t imagine that’s necessary for this to function so I think it’s fair to say it’s a bad design, if not outright malicious.
It looks sketch and this is the kind of thing that could really benefit from a small explanation. Users land on what seems to be a joke/novelty website that is immediately asking them for google login information, with no explanation. As you can see from the reactions here, that did not go well. An explanation of the reason for the login would help a lot.
I'm not logging in with Google to anything. Please classic any-email or no-email (like here on HN) registration only (and don't forget to allow changing usernames and emails). As long as it is necessary. Better no registration at all. I used to be among the early OpenID enthusiasts preferring to sign-in with Google everywhere, then I realized what the actual pros and cons are and concluded that's not worth it.