Half-Life 3's Original Pitch Was For A Procedurally-Generated Rogue-Lite
Through many iterations on the sequel, Valve took inspiration from Left 4 Dead for one idea that nearly stuck.
Since the release of Half-Life 2: Episode 2 in 2007, Valve has gone through multiple iterations of a potential Half-Life 3. One such idea would've turned the game into a replayable rogue-lite of sorts, after the success of the Left 4 Dead franchise.
The idea, detailed in Geoff Keighley's Final Hours of Half-Life: Alyx, was in development during 2013 and would've added an element of proceduralism to Half-Life. Players would have to navigate a procedurally generated building to save a prisoner and engage in random enemy encounters. More traditional story elements would've been served in-between these runs, but the core principle would be replayability. It would have been a drastic change from the bespoke environments and extremely narrative-heavy gameplay of the previous two games and DLC.
The idea was ultimately canned, but not for straying away from the foundations of the series. Instead, this version of Half-Life 3 suffered from development issues with Valve's Source Engine 2, which made development challenging. Source 2 was missing features such as lighting, save functionality, and visibility options, which compounded with the difficulty of modelling outdoor areas in an engine more suited to blocky interior ones. These issues contributed to the cancelation of this Half-Life 3 iteration, as well as a proposed Left 4 Dead 3.
Valve also had an RPG in conceptual phases at the time, with inspirations from Monster Hunter, The Elder Scrolls V: Skyrim, and even Dark Souls. One idea centered on Dota 2 character Axe, who would star in his own adventure. But by the end of 2014, Half-Life 3, Left 4 Dead 3, and this RPG concept were all shelved as work on Source 2 continued to potentially facilitate them better in the future.
Of course, Half-Life eventually did return, but not until 2020. Half-Life: Alyx isn't a structural departure from previous entries in the series, but the decision to make it a VR exclusive was a way for Valve to try something new with its gameplay. Alyx reportedly represents at least the sixth attempt at a Half-Life sequel since Episode 2. Considering its warm reception and the way it continues the central story, it might be the revival the series needed. You can purchase The Final Hours of Half-Life: Alyx on Steam now for $10 for more insights into its development, as well as other stories on other cancelled Valve projects.
Being playable on a range of VR headsets allowed as many people as possible to experience the next chapter of Half-Life, but it was the way in which it used the platform that made it stand out. GameSpot's 9/10 Half-Life: Alyx review breaks this down, with critic Michael Higham writing, "Even when familiarity starts to settle in, its gameplay systems still shine as a cohesive whole. And as it concludes, Half-Life: Alyx hits you with something unforgettable, transcending VR tropes for one of gaming's greatest moments."
Half-Life: Alyx Review And Guides