Mastering Unity 2D Game Development

Developing 2D Games with Unity: Independent G- paperback, Halpern, 9781484237717

Beginning 3D Game Development with Unity 4: All-in-one, multi-platform game development (Technology in Action)

Unity in Action: Multiplatform Game Development in C#

GameMaker Programming By Example: Master the development of 2D games by learning to use the powerful GameMaker Language and tools provided by the GameMaker: Studio workspace and engine!