Gamers who just have to have id's first-person shooter, Doom 3 for the Xbox, first thing Monday can now do so. Game Rush, Blockbuster's gaming branch, will be opening its doors just after midnight to sell the game as soon as it goes on sale on April 4. In addition to selling the limited and standard editions of the game, Game Rush will also sell Xbox accessories for 20 percent off, and the Doom 3 strategy guide will sell for 30 percent off. Members of Texas-based id software, the game's developer, will be on hand at the Game Rush store on 6437 Hillcrest Avenue in Dallas to meet fans, sign autographs, and give away Doom 3-related merchandise. Doom 3 is rated "M" for Mature and will sell for $49.99. The limited edition, which includes playable versions of Ultimate Doom and Doom II, will sell for $59.99.