Valve has patched the PC demo of Left 4 Dead to remove split-screen play, which could be activated by plugging in an Xbox 360 controller and typing a short console command.
"Split-screen was always something we only wanted to officially support on the x360 due to the controller issues. However, we are planning on making some of the functionality work on the PC as an unsupported bonus feature," said Valve designer Yahrn Beriner on the Steam forums.
"We turned it off for the demo because we didn't want to have to deal with any additional bug reports etc. about it interfering with the demo experience, but the current plan is to re-enable it after we launch the full product."
And when that happens, Beriner believes the best split-screen set-up on PC will be two joysticks or two Xbox 360 controllers. One on keyboard/mouse and one on joystick should also work, although he's not sure about two lots of keyboard/mouse input.
Split-screen was just one of the features unlocked by savvy internet goers in the demo; the ability to play as the Infected and load user maps is also possible.
The Left 4 Dead demo launches worldwide on PC and Xbox 360 today, and will let quartets of survivors pit their wits and firepower against the relentless and frenzied Infected.
The full version of Left 4 Dead will be available on Steam from 18th November, while retailers will stock PC and Xbox 360 copies from 21st November.