Posted link in a comment of a different discussion but decided to make new post for everyone.
kitten showed up on the door step about the first week of January. We've taken it in and it acted like it already knew to use a litter box. It will go out side daily several times, but many times it comes back in the house to use the litter box. It seems to already doubled in size.
I don't know if I have ever seen a cat that would entertain itself so much playing with things.