A HP bar system, feel free to change the MAX HP and HP variables in the second sprite. When the bar is going up to start with, put it in turbo mode (shift + click the green flag) then do it again when it's got to the top. Space is to damage, which you can also change by changing the damage variable before the repeat damage script. And yes, HP can be different from MAX HP, although it looks weird if you make HP more than MAX HP. I think that's all. Have fun ;-3
Feel free to use it in your own game but give credit to me - AriArk!