Construct is a free powerful and easy to use development software for both DirectX 9-based games and applications,in a WYSIWYG environment. It includes an event based system for defining how the game or application will behave, in a visual, human-readable way - easy enough for complete beginners to get results quickly. Optionally, advanced users can also use Python scripting to code your creations.
For Windows XP/Vista/7. A graphics card with pixel shader 2.0 and at least 64mb of video memory is recommended.