The license says it's GPLv3, but with the further restriction that "It is prohibited to make a derivative work that has server-syncing capabilities."<p>The two relevant sentences in the GPLv3 are "You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License." and "If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term."<p>This means that (1) if Pororoca contains any GPLv3 code from anyone else, then their copyright is being violated, and (2) anyone is allowed to make such a thing anyway, since the GPL allows that term to be removed.