Digital Game Engine Resources
Lists:
Easy:
Scratch <http://scratch.mit.edu/> - Game engine designed for kids. Free (Mac, PC, Linux)
001 Game Creator <http://www.engine001.com> Easy graphical scripting engine. (PC)
Easy/Medium:
Stencyl <http://www.stencyl.com/> - Simple game engine for 2D games. Free (Mac, PC, Linux)
Construct Classic <http://www.scirra.com/construct-classic> - Simple 2D game engine. Free (PC)
Gamemaker <http://www.yoyogames.com/make> - Simple game engine. $40 shareware. (PC, Mac*)
PyGame <http://www.pygame.org/> - Simple game engine. Free (Linux, Mac, PC)
Hard:
Unity <http://unity3d.com/> - Professional game engine. Free* (PC, Mac)
Unreal <http://www.udk.com/> - Professional game engine. Free* (PC)
Godot <https://godotengine.org/> - Professional open-source game engine, Free (PC, Mac, Linux, Web-hosted)
Crytek <http://mycryengine.com/> Professional game engine. Free* (PC)
Additional List - <https://secure.wikimedia.org/wikipedia/en/wiki/List_of_game_engines>