Even though I am not a gamer, I realize that many of our students do learn via game mode. Maria Vella reminded me of Prodigy. This free/subscription site will have you solving math problems to earn points and cast spells. Not for every student ( I was easily distracted by the music) but something you might want to try. There is also a paid version (with more options as well as in App purchases). So create a free teacher account and create codes for your students.