This article is about a mod.
Operation Black Mesa is an upcoming modification for Half-Life 2 and a complete Source conversion of Half-Life: Opposing Force. While it could be considered as a companion to the mod Black Mesa, the two developer teams are not associated.
Valve Corporation originally had plans to port Half-Life: Opposing Force into the Source engine (announced at E3 2004) much like they did with Half-Life: Source, but after seeing the results of the port the Operation Black Mesa devteam decided that it wouldn't be worth the wait, and thus took the task into their own hands. They began in September 2007, one month before the release of Half-Life 2: Episode Two.
On December 4, 2008, the old forum website was shut down due to hackers. According to the project leader they were not aware of the team member that had assisted in the hack.
On November 2, 2009, the team released a huge media update to celebrate the 10th Anniversary of the release of the original game. Also, the project leader announced they hired new members to help with the project.
In early 2012, the team merged with the Guard Duty Team to form Tripmine Studios, to make the work much smoother. At the same time, they publicly released an update.
On May 1, 2012, team released more media of screenshots along with the Guard Duty for the second update after the merge.
On August 21, 2012, they announcing the Multi-player section in the Original Game to invitation for every fan that like to participated their meeting event to discussing how to improving both projects into much better respective view. Also, the team released both the model of RPG and Automatic-Turret for the update. .
On December 8, 2012, mark the fourth update media after the merge following the event of MOD of the year 2012. 
On February 17, 2013, the team announcing the Greenlight for both projects to be in Steam after the development is finish. At the same time, they release more screenshot and concept art for the projects. .
On March 23, 2013, they release update the first part of media for the month. .
On April 1, 2013, they release more media for the second part of the Greenlight update and announcing the trailer in the near future. .
On May 17, 2013, they release third and final part of the conclude Greenlight media update. 
On July 29, 2013, they have announced that Operation Black Mesa have greenlight and awaiting the decision to be in Steam. At the same time, they have update the media to keep on the pact and the released date for the Beta Multi-Player for Project. .
On December 20, 2013, they thanks every fan for voting in the event of MOD of the year 2013. At the same time, the team released another update version of "We Are Pulling Out" screenshot. 
On March 26, 2014, they update another media update and announced that the Beta Multi-Player have cancelled. 
A list of features planned for the final release:
- Complete re-creation of all twelve chapters from the original game.
- Models that push the limits of the Source engine.
- Multiplayer, including Deathmatch and Team Deathmatch with all the original levels fleshed out. A "capture the flag" mode may be included, but not in early releases.
- New voices, sounds, and visuals.
- Level design tweaks to utilize the advanced physics engine introduced in Half Life 2.
- A remixed soundtrack including enhanced music from the original along with new tracks.
- New scripted scenes.
- Mod DB – Top Unreleased Mod for 2007 (5th place)
- Mod DB – Honorable mention for Top Unreleased Mod for 2009
- Mod DB - Mod of the year 2010 - Players Choice (3rd Place)
- Mod DB - Honourable mention of Top Unreleased Mod of 2011 
- Mod DB - Best upcoming Mod of 2013 (1st Place) 
- ↑ http://lambdageneration.com/posts/operation-black-mesa-and-guard-duty-the-two-gearbox-expansion-remakes-join-forces-and-merge-into-one-team/
- ↑ Tripminestudios forums
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/project-relaunched-new-leader
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/unforseen-consequences1
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/ten-years-of-opposing-force
- ↑ http://www.planetphillip.com/posts/operation-black-mesa-and-guard-duty-interview/
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/operation-black-mesa-and-guard-duty-update
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/report-for-duty
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/guard-duty-and-operation-black-mesa-moty-update
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/greenlight-incoming
- ↑ http://tripminestudios.com/forum/showthread.php?tid=39
- ↑ http://tripminestudios.com/forum/showthread.php?tid=107
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/greenlight-report
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/operation-black-mesa-has-been-greenlit
- ↑ http://www.moddb.com/mods/operation-black-mesa/news/operation-thank-you
- ↑ http://tripminestudios.com/forum/showthread.php?tid=392
- ↑ Mod DB Top Unreleased Mod for 2007
- ↑ Honorable mention at the Mod DB Top Unreleased Mod for 2009
- ↑ http://www.moddb.com/events/2010-mod-of-the-year-awards/features/players-choice-upcoming-modification-2010
- ↑ http://www.moddb.com/events/2011-mod-of-the-year-awards/top100
- ↑ http://www.moddb.com/mods/operation-black-mesa/features/best-upcoming-mod-of-2013-players-choice
- Official website (Studio website)