Single Board Computer

Hello everyone,,
My 13yo nephew is interested in a single board computer for playing around with and learning how they work. I am looking for one for him, but I do not know much about them. He wants to try a little programing, but wants to be able to play Runescape 3 on it too. That is the only game he likes. He wants to run windows 10 on it. I want to go as low as possible on price until I know it is something he will be interested in for the long term and then get him some better stuff later on, so I was wondering if anyone here had any good suggestions for a cheap starter board that meets these qualifications. Thanks.