9. Half-Life: Decay – November 2001
When Gearbox ported Half-Life to the PS2, they also created a new mini-expansion for the console version. This was Half-Life: Decay, a co-op game focused more on puzzles. Of the Gearbox-developed Half-Life expansions, it’s the most different from the main Valve-developed Half-Life. It’s a short side adventure set during the events of Black Mesa and starring two women who are colleagues of Dr. Freeman. And while it was never officially ported to PC, fans have done the work and you can now play it on your computer with online play, something the PS2 port didn’t support.
