Uhm, actually, pertaining to the earlier ask about a normal session? It would be more like the dancestor's session. (which they only failed at because they were bad players.) Jack wouldn't be there, and if he was, he wouldn't actually be a part of the plot like he was in the post-scratch troll's session or in the Beta kid's session! :) Also, in Karkat's session, the created universe wouldn't have a Tumor.