libRocket is the C++ user interface middleware package based on the HTML and CSS standards. It is designed as a complete solution for any project's interface needs.

libRocket uses the time-tested open standards XHTML1.0 and CSS2.0 (while borrowing features from HTML5 and CSS3), and extends them with features suited towards real-time applications. Because of this, you don't have to learn a whole new proprietary technology like other packages in this middleware space.

Kong is an great free 3d FPS and its also powered by libRocket!

We put together this entry in to the three-week VGNG competition at TIGSource, using libRocket for the interface. Check out No One Can Stop The Farm Pioneer!

Packed with features!

• Cross platform across all desktop environments: Windows, Mac OSX (Intel) and Linux.
• Dynamic layout system.
• Efficient application-wide styling, with a custom-built templating engine.
• Fully featured open source user control set: buttons, sliders, drop-downs, etc.
• Runtime visual debugging suite.
• Easily integrated and extensible with Python scripting.

Extensible:

• Abstracted interfaces for plugging in to any game engine.
• Decorator engine allowing custom application-specific effects that can be applied to any element.
• Generic event system that binds seamlessly into existing projects.