Cute lil game! I like that it gets naturally harder because the chickens are less and less, and harder to catch. You could increase the player movement as others have suggested, or maybe the chickens that the player can carry to 10. It's a bit annoying to return for every 5 chickens and the fox doesn't have to return to the coop at all so it's hard to beat it. You might need to explain better that you can carry only a certain number of chickens and you have to return them to the coop before you can gather more. Great game overall!