How height, audio cues, and trust sculpted VR locomotion in Half-Life: Alyx

“Movement in VR generates so many more player expectations because the world completely envelopes the player.”

- Valve's Greg Coomer offers a deep dive into the different movement systems at play in Half-Life: Alyx.

Creating comfortable and believable movement for players in virtual reality is one of those game development puzzles where there isn’t a one-size-fits-all answer. It’s a problem many, many game developers have tried to tackle, and even VR veterans like Valve are no exception.

In a recent developer commentary video, the Half-Life: Alyx team share how they approached tackling this particular problem and walk fellow developers through the variety of odd issues and scrapped systems encountered along the way.

The eventual solution evolved into three potential systems players are free to choose between: a blink teleport, a shift teleport, and a continuous locomotion. Prototypes of those teleport options started off with fixed teleportation locations, a la Valve’s early VR venture The Lab, but the system didn’t quite jive with the feel of Half-Life: Alyx.

Instead, the teleport evolved into a system that shows players a cursor shaped like a pair of spectral legs to help players better process how they’ll exist in the space after moving. Other visualizations and audio cues eventually came into play to deepen that connection as well, discussed in depth in the video above.