(for some reason after using five, you may need to click the phase you want to see a few times to get rid of the souls) press the flag keys 1-5 for phases themes: 1 - just doing 2 - blue boned brawl 3 - Perplex Prime 4 - MEGALOVANIA 5 - it's finally raining Story: The basic story of this is that the human is going through a genocide route, but papyrus warns sans, and tells him to "practice your dodging, ok." and while sans is fighting the human, he does so. the fight leads on normally until sans gets tired. the human is just about to kill him, but papyrus runs in to take over the fight. as he's fighting he tells sans to run to toriel's. while he's there toriel supplies sans with the six souls, and all the monsters are gathered there. he doesn't know what they want him to do at first but then toriel tells him to absorb all of the souls of the monsters. then sans' power becomes godlike...
credit to the original creators of the themes someone else made the soul engine but i don't know who