Black Mesa (previously known as Black Mesa: Source) is a third-party total conversion modification for Valve Corporation's Source engine. The stated goal of the project is to recreate Valve's critically acclaimed 1998 video game Half-Life using the more advanced capabilities of the Source engine. The 40-person volunteer development team says they hope to create a more engrossing in-game world with more varied, complex environments and more challenging, realistic gameplay.
During its eight years in development, Black Mesa has been featured in several video game publications and received direct attention from Valve. Due to its long development time the modification became notable for its delays, and dwindling updates on the status of its completion. The delays led to Wired awarding Black Mesa high spots on their "Vaporware Of The Year" lists in 2009 and 2010.
The first part of Black Mesa, featuring remakes of all Half-Life's chapters except those set on the alien world "Xen", was released as a standalone download on September 14, 2012. Public voting through Valve's Greenlight program saw the game approved for distribution on Steam.
Black Mesa is a first-person shooter that requires the player to perform combat tasks and puzzle solving to advance through the game. The core gameplay remains unchanged from the original Half-Life; the player can carry a number of weapons that they find through the course of the game, though must also locate ammo for most weapons. The player's character is protected by a hazard suit that monitors the player's health and can be charged as a shield, absorbing a limited amount of damage. Health and shield packs can be found scattered through the game, as well as stations that can recharge both.
The primary difference in gameplay from the original Half-Life is the ability to use the Source engine's physics to influence gameplay elements. The original Half-Life engine based on the GoldSrc engine, lacked such physics, with certain events or situations instead hard-coded as animations, such as a toppling stack of boxes. With the Source engine, these physical effects can be handled directly by the engine, allowing the player to initiate such actions to their advantage, or to make certain challenges more difficult such as jumping across a number of crates suspended by cable from a conveyor system.
Source: Wikipedia, "Black Mesa (video game)", available under the CC-BY-SA License.