Resources
Game Engines
Twine
Twine is an open-source tool for telling interactive, nonlinear stories.
RPG Maker
RPG Maker is an commercial tool for creating top-down 2D role-playing games.
GameMaker
GameMaker is best suited for 2D games, it can be quite powerful and it has less steep learning curve compared to Unity.
Unity
Unity can be used to make both 2D and 3D games alike, previous experience with programming is recommended.