I would recommend doing these as HTML5 games. That way they are playable on any platform that can view a Web page, such as desktops, laptops, tablets, mobile devices, etc. This would also make it very easy to bundle the games with your books.
My bid is for one simple game and assumes you need me to do the game design and graphics as well, but if you already know what kind of game you want, even better.
Please let me know what your requirements are and if you have any questions. Thanks.