The closer the cats get to the goal, the bigger their fitness is. Basically, the cats try to get to the other side. The one that gets the furthest has its genes pass on to the next generation, while all the others die. They start with only 40 moves(left, right, up, nothing), and they gain 20 each generation.
the people get to stairs - 14 climb the first step - 14 climb to the second step - 21 finish -
