Following my previous question, that mean that if the space player didn't complete his quest in time, the group just need to defeat the black king? that's kinda against the whole 'Time limit' of SBURB

That’s a good question but I’m not quite sure how much of the Session would require simultaneous stuff. Likely you can use all that extra time once the Reckoning has stopped and just go do the Denizen and Frog Breeding afterwards? I mean for all intents and purposes as long as the Session doesn’t Detonate or die off from some external factor, you don’t even need to Win to have like, several planets and cool powers to take advantage of, so maybe.