Was made in 2021 year with pure JS and canvas API. Original code is 3kb. Basically it's random walker that paints rects.
Click is open popup with current picture that can be saved as file.

Features:
Background - one of colors 'Deep Jungle Green', 'Dark Slate Gray', 'Raisin Black', 'Dutch White', 'Pansy Purple'
Rects Count - count of walker steps, count of rects
Width - usual is 1500px, sometimes it's 5000px (around 15%)
Width - usual is 800px, around 15% is 5000px