Left 4 Dead free this Friday

Playable demos have become an established marketing vehicle in recent years, but Valve is taking it one step further tomorrow by allowing anyone to download and play its hugely popular Left 4 Dead for free.

Kotaku reports that from midnight tonight anyone with a PC and a Steam account will be able log in and download the game in its entirety until last thing Friday night. The download normally costs 26.99.

Once the trial is over, however, free versions of the software will be locked and gamers will have to buy the full version to carry on.

Anyone interested in downloading the game will be able to pre-load right now, reducing the chunk of the free 24 hours spent downloading the title.