Prima is now offering Eguides for many of Valve games. Here's more info and links for purchase:
Half-Life® 2 In Half-Life 2: Prima's Official Eguide, you get essential strategies and maps for all 14 mission chapters. Also included are complete bestiary tactics (including how to take on the monsters and Combine forces), in-depth evidence of all G-Man locations, and deep combat strategy against the oppressive forces of evil. Full-color maps show every major item location. Also get dozens of tactics for using the Zero Point Energy Field Manipulator. Finally, we expose key script, backstory, and hidden game elements!
Counter-Strike™ (Xbox) Counter Strike: Prima's Official Eguide has full coverage of all Counter Strike missions with maps and key locations identified. In-depth counter-terrorist and terrorist tactics help you complete each mission. Also get a complete inventory of weapons and gear, strategies for handling hostage and demolition missions, and locations for the best camping spots and sniper positions.
Counter-Strike™: Condition Zero™ Counter Strike: Condition Zero--Prima's Official Eguide gives you proven single-player strategy for all missions, detailed maps and outlines for each mission, and lessons in how to use new weapons and equipment (including the M60, LAW Rocket, and Shield Gun). You even get strategies for playing as a Counter-Terrorist. Also included are tips on hostage rescue, bomb defusal, and VIP Escort. Get more out of your game with secrets and cheats. Finally, our multiplayer strategies could make you a better online contender!
Day of Defeat™ Day of Defeat: Prima's Official Eguide gives you detailed maps of all 15 game areas, comprehensive mission strategies, and stats on every class of soldier. Weapons and equipment stats for both Allied and Axis fighters and hints for getting the most out of your arsenal help you get more out of the game. Dominate your friends with our multiplayer strategies, or be everyone's favorite comrade with our tips for team-based gameplay.