Or if you have a 360, there are a couple that would do the same kind of thing. For example, if you have a PS2, there's a gadget that does the same thing. Use a gaming controller for the second player- just make sure it's a keyboard and mouse. What you really need is something that would let a console operate a keyboard and mouse as if it were a controller. You could easily use a lot of similar devices. Also: In this tutorial I use the Smarjtoy Frag Xbox controller modifier. I'm going to move quickly over a few things that will take many people a while to work through, and link to a few different tutorials that should help. This instructable will teach you how to use this unsupported feature and a variety of hardware and software modifications to use TWO keyboards and TWO mice on one computer. So, the good men and women at Valve kept it in the code for the PC version too. It was implemented on the Xbox 360 version of the game.

Background: Left 4 Dead has had an unsupported feature from the very first demo that allows individuals to play with two players on one PC. Love L4D? Want to play on one PC with 2 players, 2 keyboards and 2 mice? Then follow me, to freedom from the controller.

L4d2 split screen pc