CodeCombat is described as 'online game that teaches programming to learners as young as 6. Students write code in real programming languages' and is an website in the Development category. There are more than 10 alternatives to CodeCombat, not only websites but also apps for a variety of platforms, including Windows, Linux, Mac and Steam. The best alternative is Code.org, which is free. Other great sites and apps similar to CodeCombat are CheckIO (Free, Open Source), CodinGame (Free), Screeps (Paid) and Robocode (Free, Open Source).
Code.org is a non-profit whose goal is to expose all students to computer programming. We believe that computer programming is a liberal art; it's something EVERY student in the world should be exposed to at some point in their childhood education.
Screeps is a massive multiplayer online real-time strategy game. Each player can create his or her own colony in a single persistent world shared by all the players. Such a colony can mine resources, build units, conquer territory.
Robocode is a programming game where the goal is to code a robot battle tank to compete against other robots in a battle arena. So the name Robocode is a short for "Robot code". The player is the programmer of the robot, who will have no direct influence on the game.
CSSBattle is an online CSS Code Golfing battleground. Here, players from all around the world try to visually replicate "Targets" in smallest possible CSS code and battle it out to get to the top of the leaderboard. Are You Game?
Colobot Gold is modified version of the original Colobot game released by Epsitec under open source (GPLv3) license. Source code was refreshed and rewritten using SDL and OpenGL libraries, thus making it multiplatform
VIM Adventures is an online game based on VIM's keyboard shortcuts (commands, motions and operators). It's the "Zelda meets text editing" game. It's a puzzle game for practicing and memorizing VIM commands (good old VI is also covered, of course).