# Where does the alien go when it climbs into the vents?

- Series: [How It Spawns](https://miu.fm/howitspawns.md)
- Published: 2026-10-31
- Page: https://miu.fm/howitspawns/where-does-the-alien-go-when-it-climbs-into-the-vents

## Story

Where does the alien go when it climbs into the vents?

In Alien: Isolation (Creative Assembly, 2014) one alien hunts you through a whole space station. Its makers first built a hunter that could find you anywhere. Designer Gary Napper: "it turned out that it wasn't very fun", "because it just knew where you were." So it hunts by its senses: "he can hear you, he can see you and he sees movement and light."

And now and then it climbs into the vents. To move, it needs a navigation mesh, a map of the floor. Lead AI programmer Andy Bray asked the level designers to lay one in the vents. There weren't any: nobody had left room, and lifting the floors would have broken the stairwells and cost hundreds of hours. In Bray's words: "the vents are entirely fake."

When it climbs in, the game turns it invisible and slides it along the x axis, then the y axis, then the z axis until it reaches another vent exit, and it drops down. With a debug camera you can see it pop onto the floor above, or out into space if there's no floor. One early bug: the motion tracker put it 20 meters away through a window, outside the ship, so they added invisible walls to keep it in.

The station, the alien and the slide are our own simplified version, run in code.

Did you ever hide under a vent?

Sources: Andy Bray (lead AI programmer), Alien vs. Predator Galaxy podcast, 10th anniversary retrospective, 2024; Gary Napper, interview, GamingBolt, 2014.
Sounds and music: our own, made in code.
Unofficial. Not affiliated with or endorsed by Creative Assembly, SEGA or 20th Century Studios. Alien: Isolation is a trademark of its owners.

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