Half-Life 3, Left 4 Dead 3, and other canceled Valve projects detailed in new documentary

New details have emerged about a number of unreleased high-profile Valve projects, including Half-Life 3, Left 4 Dead 3, and a handful more.

The information comes from Geoff Keighley's Half-Life: Alyx - Final Hours (via IGN), an interactive storybook that gives insight into development on Alyx and plenty other Valve IPs.

Starting with Half-Life 3 - which was canceled along with at least four other Half-Life games before Half-Life: Alyx was eventually released - Keighley reveals that the sequel was developed in the unfinished Source 2 engine and featured some gameplay elements inspired by the Left 4 Dead series. Further, in between cutscenes would be procedurally generated elements like buildings filled with enemies and escape routes, making every such scenario play out differently. Sadly, Keighley says Half-Life 3 was canned in 2014 after about a year in development.

As for the Left 4 Dead sequel that would never rise from the dead, it was set to take place in Morocco, where players would encounter hundreds of zombies at once in an open-world setting. That project was eventually deemed too ambitious for the still-unfinished Source 2 engine to handle.

Other revealed Valve projects include an unnamed RPG inspired by games like The Elder Scrolls and Dark Souls, a Half-Life themed VR shooter that used only Half-Life 2 assets, and another idea for a Left 4 Dead game that wasn't detailed. There's also Borealis, a Half-Life VR shooter that would've time-jumped from the Half-Life series' Seven Hour War and some time just after Half-Life 2: Episode 2. 

It's bittersweet learning about the bones of so many enticing Valve games we'll never get to play, but it's not outside the realm of possibility that the studio resurrects one or more of them. Just a year ago, no one would've believed a Half-Life VR game would come out in 2020.

Don't forget our essential Half-Life: Alyx tips for surviving in City 17.