Valve has recently added a new feature to Left 4 Dead 2, the Extended Mutation System. Sounds exciting? Well it is, but not exactly in the way you were expecting. Rather than as its name suggests, it is not a gameplay addition in the form of handed-out mutations (though that would be awesome), but instead a complex modding system through Valve's gift of an expanded scripting toolset.

Valve has long since been a great supporter of mods and what they can bring to the world of gaming, and here it is no different. It states that the system would “allow script authors to go past modifying existing scripts and write custom script logic, spawn and control entities, and much more.” Yes, that is exactly as it implies - an immense treasure chest of possibilities to which Valve has just given us the keys.

Currently the system is in beta testing, where requests to join may be made here, but prepare yourselves to see a whole flood of new and interesting mods to hit the scene any day now...