I have found that not only does this encourage turn taking and counting skills as you keep tabs on how many mice you have in your pile, but it also brings in the language of addition and subtraction. We talk about how many we have now one has been taken away or added. There is talk about more and less. The children start to recognise and estimate how many mice are in a pile just by taking a glance.
If you ever come across this game I really recommend it as a great addition to your collection. It has become a firm favourite in my setting!