The only issue I see is in the act method of the MyWorld class. You reset the timer back to 0 when it reaches 200, so, it will never get to 400, which the next if statement checks for.

Thanks danpost! That totally explains why the cows weren’t spawning — I had no idea the timer reset was messing with the later condition. I’ll go fix that now. Also, just wanted to say I haven’t been on Greenfoot for long, but I’ve already noticed how active and helpful you are. Your replies are quick, spot-on, and actually help people level up their code. Big respect — keep doing your thing!