Same. Use your mouse to move. You are the red square. Avoid other squares, but when the "Charged:" shows "Yes", you can press space to activate a destroyer shield, killing nearby squares, with a 2-second cooldown. Killed squares award 5 points. Watch out! The enemy could appear from any side.
Because the invading squares are increasing, the Retro Brush has transformed into a red destroyer robot that can destroy anything nearby. Retro Brush: https://scratch.mit.edu/projects/529798866 Credit to @BrandonGamingAV80 for the enemy retro. Music: https://www.youtube.com/watch?v=E-uo24zc2I8 Destroyer Sound Effect: https://www.youtube.com/watch?v=18sbp66w0WA