© 2004 Valve Corporation. All rights reserved. Valve, the Valve logo, Half-Life, the Half-Life logo, and the Lambda logo are trademarks and/or registered trademarks of Valve Corporation.Sierra and the Sierra logo are registered trademarks or trademarks of Sierra Entertainment Inc., in the U.S. and/or other countries. Vivendi Universal Games and the Vivendi Universal Games logo are trademarks of Vivendi Universal Games Inc. All other trademarks are property of their respective owners.