Gamemaker:About

About GameMaker
GameMaker allows you to make exciting computer games without the need to write a single line of code. Using easy-to-learn, drag-and-drop actions, you can make professional-looking games in no time. Games can have backgrounds, animated graphics, music, and sound effects, and once you get more experienced there's a built-in programming language that gives you full flexibility. What's best, the "Lite" version of GameMaker can be used completely free of charge, and you can use the games you produce any way you like. You even can sell them. The Lite version can be found here. 

You don't have to be able to program to be able to make games with GameMaker, though it does have a built in programming language to give you full control of your game if you want.

GameMaker comes in two versions: Lite and Pro. Lite is free of charge, but for a small amount of money ($39.99 or less), you can buy the full version which has lots more features. An upgrade that is definately worth the money.