From Black Mesa: Wiki

The main feature and goal of Black Mesa is its attention to environment detail. Levels will be faithful to the original Half-Life concept, but built completely from scratch, featuring higher-resolution textures, detailed world models, and a higher quality of audio ambience courtesy of the Source Engine's soundscape system. The end goal of such attention to detail will be an immersive environment, plunging anew the player into a story that is yet to be matched by any other first-person shooter.