This is a boss battle. Drag the square around or use WASD to move and survive for as long as you can. My high score is 178 Volume Controls below: Up and down arrow keys to change volume (up and down respectively) M to mute and unmute (cannot change volume up or down when muted). Muting the volume saves your previous volume when you unmute it.
Play my other project, Square Super Game (this is supposed to be its lvl 10 but then I decided to just make it a separate project) https://scratch.mit.edu/projects/992384328 This is actually a 'survive as long as you can'-type thing, there is no 'defeating' the boss