Its an evolution thing.
You input the number of creatures (2 to 15)
Creatures has to be 2 or more because for evolution to happen at least one creature must die per round, and with only one creature it just dies and the game ends.
Creatures has to be less than 16 because Scratch works funny and will not allow more than 15 clones code start at the same time. At 15 they all start simultaneously.
Number of rounds (1 to infinity)
The ones that finish first reproduce more.
Sometimes the change will make them slower.
Their speed is indicated by their color. Pink is the slowest and then it goes through the rainbow up to blue which is the fastest.
</p>
<a href="https://scratch.mit.edu/projects/852105682/">Link</a>