The rule could be anything, as funny or as serious as you want. The universe will progress in a similar way that it has up until this point, unless your changed rule prevented it from doing so.

Some examples might be:

  • The invention of currency is not allowed.
  • Iron is slightly less stable.
  • The Ancient Greeks are able to cultivate Silphium, which does not go extinct now.
  • Makr Alland
    26•19 days ago

    No quantum mechanics. Things have concrete properties even when no one’s watching, and they can all be observed at the same time. The universe is complex but understandable.

    Also, P=NP and π is 3.33 repeating, just for the lols.