Really Bad Time Sans was one of the two fanon characters to be added to Undertale Judgement Day when it was released, the other one is True! Dust. This is a version of sans that acts closer to how he is depicted in Undertale, rather than the easy fight that classic sans has in judgement day. Just like in the original game, almost all of his damage comes from his KR rather than the actual attack itself and without it his damage output is extremely low.