To generate a maze, click the green flag. If you just want to see the generated maze rather than the process, use turbo mode (shift + green flag).
This is a visualization of the "randomized depth-first traversal" algorithm, which is used to generate mazes. Here, the areas considered by the algorithm to be dead-end are marked with color. I have already implemented this algorithm in JavaScript: https://codepen.io/micnap818a/pen/gjggGp
