Bad Time Simulator
Are you a fan of Undertale? If so, then this project is perfect for you. Bad Time Simulator will give you an exceptionally challenging experience on fighting with one of the strongest characters in the original game.
You were able to fight Sans only on the evil root, but if you want to do it without completing the whole story for the second time, you may take part in the battle here. You will immediately start with the confrontation, so prepare to fend off the attacks.
During the battle, you will have several choices. You may try to talk with the opponent, to strike or to apply an item. When you reach the point where the opponent is weakened, you can also refuse fighting and let Sans go. However, it will be hard to get to this point, as before you will have to survive under hundreds of strikes.