An early Half-Life: Alyx ‘bug’ turned out to be tall players crashing into virtual pipes

"We would get hard-to-reproduce bugs from players banging their virtual head on low-hanging pipes"

Half-Life: Alyx is an huge technical accomplishment and marks an exciting leap forward in VR gaming, but it seems developer Valve encountered some perplexing hiccups during its creation. At one point, the studio was faced with “hard-to-reproduce bugs” that stopped players teleporting in certain spots – and it turns out it was taller players banging their virtual heads on in-game pipes.

That’s according to a new ‘Locomotion deep dive’ clip posted by Valve (via RPS), in which the studio takes a look at player movement in Half-Life: Alyx – “and some of the more interesting things we learned along the way”. One of these examples, Valve dev Greg Coomer explains, ties into ‘viable pathing’. “It turns out that the height at which players view the virtual environment is very important,” he shares.

“Early on, we would get hard-to-reproduce bugs from players banging their virtual heads on low-hanging pipes because they were unable to teleport through certain areas,” Coomer says. It turns out, the devs realised later on, these ‘bugs’ were only originating from the taller colleagues playing and testing the game.

“We as humans are strongly attuned to the perspective that our height gives us on the real world, and it was essential that we preserve this in the virtual environment in Half-Life: Alyx,” Coomer explains. He says the result of this phenomenon is that each player’s real-world height has an impact on the “extent” of their in-game body – and by extension, their perspective in the game’s world.

This, he shares, has a knock-on effect on how the VR game’s paths are computed. You can see this for yourself in the video below from around the 4:30 mark, where Valve compares the in-game perspectives of players of different heights.

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If you’re tempted to dive into the game for yourself, be sure to take a look at our Half-Life: Alyx review. Dustin Bailey scores it a nine out of ten, concluding that the game “confidently serves as both a vindication for the magic VR can bring to gaming, and a satisfying new entry in the beloved Half-Life series.”