GameMaker is a Windows and Mac OS IDE which allows users to easily develop computer games without the requirement of prior computer programming experience.
Game maker
GameMaker is designed to allow its users to easily develop video games without having to learn a complex programming language such as C++ or Java through its proprietary drag and drop system. These icons represent actions that would occur in a game, such as movement, basic drawing, and simple control structures. It is also possible to create custom "action libraries" using the Library Maker.
Graphics
GameMaker primarily runs games that use 2D graphics, allowing the use of limited 3D graphics. It supports the ability to create particle effects such as rain, snow and clouds, however not natively in 3D except through use of Dynamic Link Library.
GML
Game Maker Language (GML) is the primary interpreted scripting language used in GameMaker, which is usually significantly slower than compiled languages such as C++ or Delphi. It is used to further enhance and control the design of a game through more conventional programming, as opposed to the drag and drop system.
Platforms
GameMaker accommodates redistribution on multiple platforms. The program builds for these platforms: Windows, Windows 8, Mac OS X, Ubuntu, HTML5, Android, iOS, Windows Phone 8, Tizen, Xbox One, and Playstation.
Source: Wikipedia