How about limit some of the area,if you complete a puzzle,this area will be enterable for your villagers,I mean right at start of the VV2 you can go anywhere you want,so you should limit some of the area.And they should able to cook the fish,I mean they know how to make fire,and there should be more different kind of fish,each might be cooked well while other and not suitable for cooking but still count as foods.