Arrows to move, space to attack, dodge anything that attacks. If you are really having trouble, click b, it makes you stop taking damage. Note that you cannot get the best time if you click b. To leave the no damage mode, click the green flag, but you will have to start over.
Play the normal version here: https://scratch.mit.edu/projects/685275790/ It is possible, just very, very hard. Thanks to Tater-Tot Tunes for the music. If you see a pink and purple line rotating around the screen when you start, just click the green flag again! Thanks to @WILL_WAM for the health bar code