Black Mesa, stylized as BLλCK MESA, is a first-person shooter developed and published by Crowbar Collective. It is a third-party remake of Half-Life in the Source game engine, and has been approved and even endorsed by Valve. It was released in full on March 6, 2020 to highly positive reviews.
Joel's highlight video features him fooling around in the 2012 version of the game with cheats. Joel goes murdering all the scientists and guards in the Anomalous Materials chapter.
After the release of the final Xen chapters in late 2019, Vinny streamed an entire playthrough of the game from start to finish. Joel streamed his own playthrough of the full release starting in January 2020.