Since this is entirely event driven, you don't need to use "When the world starts" unless there is some non-event things to be done. I do see a couple of potential problems though.
- If the gorilla is less that 2 meters from the target, then the value of min passed to the random function will be greater than the value of max. I do not know how this would be handeled by Alice.
- You are moving at least 2 meters but checking if the gorilla is within 1 meter of the target. In algebra this would work, but it does not always work in Alice due to round offs. If the gorilla is a little over 1 meter from the target then moving 2 meters could put it just over 1 meter from the target in which case, the gorilla would continue to move forward for ever.
- Possibly the biggest problem with you code is really simple, the "go to Animal" method does not do anything once the gorilla is within 1 meter of the target except stop. This is where you want to turn the target invisible! The other While events are not needed, just set the target's opacity to 0 in the if part of the condition.