>A.R.T.I.: A light-hearted, voxel-based game that allowed for open-ended destruction and creation in the vein of Minecraft. One version included Half-Life 2 and Portal writer Erik Wolpaw voicing a character called King Kevin, who had to be broken out of prison using the game's tools. A.R.T.I. was later resurrected as a VR game, but was shelved as Half-Life: Alyx grew.
>SimTrek: A VR game develoepd by members of the Kerbal Space Prgram team that was also shelved during Alyx's development.
>Shooter: A Half-Life themed VR shooter that would have been a part of The Lab, Valve's VR showcase. Using only Half-Life 2 assets, it would have had players take part in short gunfights, and was designed more like a Half-Life theme park ride than an continuation of its story. However, it was deemed not to be ready in time for The Lab's release.
>Borealis: A Half-Life VR project, led by writer Marc Laidlaw, that would have been set on the time-travelling ship mentioned in Half-Life 2. Skipping between the Half-Life series' Seven Hour War, and a time period shortly after Half-Life 2: Episode 2, no gameplay details were revealed, aside from that it included a fishing minigame.
>Vader - Valve's first internal attempt to create a VR headset. Vader was designed without compromise, but was scrapped when it became clear that it was too ambitious. The team estimates it would have cost $5,000 per unit if released. Half-Life: Alyx was initially conceived to launch alongside Vader