PlayStation 2
The PlayStation 2 version was announced to be developed by Gearbox Software on November 17, 2000. It was released in November 2001. The character and weapons models are much more detailed in this version. The levels were also updated and extended based on the work from the Dreamcast port. The game also features an exclusive multiplayer cooperative mode called Half-Life: Decay, and a two player multiplayer deathmatch mode.
The Mac OS X and Linux ports were developed and released by Valve on Steam without any announcements on January 25, 2013. Both versions support cross-platform, allowing the players to play with PC users online. The SDK was also ported over to allow modders to create and compile mods for the platforms.
 Half-Life: Source
Half-Life: Source is a direct port of Half-Life to the Source engine. It was released along with Half-Life 2 on November 16, 2004. It uses the special effects and physics engine features of the new engine. According to Doug Lombardi, it began as an experiment to see what modders would experience if they attempted to bring their Half-Life mods forward to Source. The multiplayer portion was released in another package called Half-Life Deathmatch: Source in 2005. Both games were later ported to Mac OS X and Linux and released in 2013.
The Macintosh (Mac OS) port of the game was announced to be in development by Logicware on April 23, 1999. According to Rebecca Heineman, a programmer on the project, the work on the game was nearly done, and it was three weeks away from the golden master when it was cancelled on October 19, 1999.
Heineman claims that someone at Apple overestimated the number of units of the game would sell, and told Gabe Newell that they can sell half million units. Newell funded and hired Logicware to work on the project. Sierra found out that the figures they were getting were nowhere near the projected sales, and the game would not sell enough to support the ongoing development it would need to keep it sync with the updates to the PC version. This led to the cancellation of the project.
The game was designed with cross-platform capability in mind, which allowed Mac users to play with PC users online. It was cut after Sierra's decision, possible to avoid a situation of a patch breaking the compatibility between the platforms sometime in the future. It is unknown if the game was intended to have mod support. This could be done by a possible source code release to allow modders to recompile, and port over their mods.
The Dreamcast version was announced to be in developed by Gearbox Software and Captivation on February 14, 2000. It was stated that Captivation would be handling the technology work while Gearbox would create all of the new content. It was cancelled only a few weeks away from its projected release date, due to changing market conditions on June 15, 2001. The port was to feature an exclusive mission pack called Half-Life: Blue Shift, which was later released for PC as a standalone expansion pack, along with the new models created for the port.
- ↑ Valve Announces PS2 Half-Life on Blue's News (November 17, 2000)
- ↑ Half-Life 1 Beta released for Linux on Official Steam website (January 25, 2013)
- ↑ Half-Life 1 SDK update released on Official Steam website (August 31, 2013)
- ↑ Half-Life: Source Beta released on Official Steam website (September 13, 2013)
- ↑ Half-Life Deathmatch: Source Beta released on Official Steam website (September 13, 2013)
- ↑ Press Release on Planet Fortress (April 23, 1999) (archived)
- ↑ Mac Half-Life Cancelled on Blue's News (October 19, 1999)
- ↑ Matt Chat 86 on YouTube (December 19, 2010)
- ↑ Not Given Half A Chance: The Cancellation of Half-Life on IGN (June 18, 2001) (archived)
- ↑ Half-Life Dreamcast Cancelled on Blue's News (June 15, 2001)