The original game is here: https://scratch.mit.edu/projects/71816138 and written by harmssam This is mentioned in a Github issue (https://github.com/LLK/scratch-gui/issues/3803) as a project has lag and causes a problem with the Firefox browser. Scratch 3 link: https://beta.scratch.mit.edu/#262733430/
I modified it to show that the bullets create clones of themselves (which was not obvious in the original). For me, when the clone count is 15, my Firefox session often locks up. (have to click fast). Also, I always test this in full screen mode. It looks like my changes to show the individual bullet clones has made this lockup problem easier to produce. But in this version and the original the bullet clone count builds quickly. If there are 5 bullets on the screen and you click the background you'll end up with a total of 31 clones on the screen. Most of the will be overlapping.
