I wrote this article a while ago to point out some games-based approaches: http://www.gamasutra.com/blogs/RobLockhart/20130905/199667/G...

Since then, even more have cropped up: Code Combat: https://codecombat.com/ Empire of Code: http://www.checkio.org/blog/empire-code-space-strategy-game-... Code Kingdoms: http://codekingdoms.com/ Taken Charge: https://takenchargegame.com/ ComputerCraftEdu (Minecraft Mod) : http://computercraftedu.com/