The Xbox 360 demo went live Thursday morning at 2 a.m. Pacific time, while the PC demo goes live at 7 a.m. Pacific. Interested zombie hunters can acquire the demo as part of a promotion at GameStop and EB Games, and comes with a 10% discount for pre-orders.

On November 11, the demo will be made available to all PC and Xbox 360 gamers worldwide, with no obligation to purchase the full game.

The demo will end on November 18, when Left 4 Dead hits brick and mortar store shelves and virtual shelves over at Steam.