id Software has released the official playable demo (324MB) for Quake 4, allowing you to try out this sci-fi first-person shooter sequel by Raven Software. As before, this updated demo contains a single-player mission from the start of the game "where you, as Matthew Kane, battle with Rhino Squad to clear a landing zone for the main earth forces", along with the multiplayer maps "The Fragging Yard" and "The Fragging Yard 1v1" which now also work online.