This is Undertale rejuvenation but you have 999 hp for all the chapters. It might get laggy at some points. At the end chapter 4 the giant bone or Papyrus's special attack will take you down to 1 hp (It took me 30 seconds for It to take me down to 1 hp).
Check out the original game: https://gamejolt.com/games/REJUVENATION/468011
