I have some Old English game birds
https://www.backyardchickens.com/threads/some-of-my-young-flockers.1413615/post-26141158
https://www.backyardchickens.com/threads/some-of-my-young-flockers.1413615/post-24531335
They look like they might have been the start of modern game stock
Do you have pics of the hens you have?
I'm sure you would get some fertility from a 4 year old