Minecraft Education Edition
From the website: "A game-based learning platform that promotes creativity, collaboration, and problem-solving in an immersive digital environment. Educators in more than 115 countries are using Minecraft: Education Edition across the curriculum!
Various servers are set up for different learning objectives. Students can log in and explore the world of coding, with the instructions laid out for them in the game. Create your own lesson or use other instructors' lessons available on the site. Game download and yearly subscription is required, but demos and trials are also available for free.