Here is a list of game engines and tools STEM educators can use to create lesson plans and curriculum for video game based education:

Game Design Tools

This is a master resource list used by Global Game Jam participants.  Some of these resources are free and low cost. Most of these are good for middle- high school age and above. I highly recommend Game Maker and or Game Salad game engines since they have a huge community online and there are many tutorials available. You can even publish to the web, and/or test a iPhone or android device.

https://docs.google.com/document/d/1qQf5zjvJHEB40xYhTiFo9GzNYUBt8iAw8vzPu2Oy354/edit

Basic Game Design Principles

For those on the younger end, Game Star Mechanic is a free website and online ciriculum that teaches game design theory and systems thinking. https://gamestarmechanic.com/

Video Game Ed Curriculum

Their parent company E-Line Media makes educational games and curriculum for educators. Please check them out as well. http://elinemedia.com/

You may also want to join the Institute of Play for teacher support and training using video game curriculum's- http://www.instituteofplay.org/