You probably noticed numbers at the bottom left corner of your tracking device
and I bet many of you thought it was a distance between you and the alien. However it never exceeds 0.96 and when it's at 0.0 and you are not hidden at this point the alien even if he was far away from you would rush towards your location and take your head off.

I would call this number a "Safety Indicator".Say we are walking down a corridor and the alien is not around but this indicator keeps decreasing. When it reaches 0.0 the alien would screech and run towards you. If it happens hiding won't save you.

After having played the game on the highest difficulty and experimenting with stuff I've come to the conclusion that this indicator is a variable. It increases if the distance between you and the alien's "habitat" gets bigger or if the alien moves away from you. It decreases rapidly if you run or if you walk around within the alien's habitat even if he is himself somewhere far away.

When "Safety Indicator" is at 0.90- 0.96 you are safe to explore the area(checking out terminals etc). You have approximately 5 seconds.

If "Safety Indicator" is at 0.2-05 you'd better stop doing anything unless the alien is crawling in a vent and it's exit is far away from you.

You should be careful though. If he is in a vent nearby and you disregard safety measures the indicator will rapidly decrease to 0 and the alien will come after you.

Places where you can encounter the alien have a certain habitat and you are at the center of this habitat. Wherever you go the alien will always be within a certain proximity and he won't run away to the other side of the map.

To AI a player is a "beacon". The alien is always where we are. However habitat shifts with a relative time delay. So if we suddenly leave habitat the alien would come to us only after 10 seconds or even half a minute if we moved far away silently and fast enough.

It allows us to buy some time. While the alien is crawling somewhere within a previous habitat we have already got to a different place. But if we stay there too long his habitat will shift to where we are and he will be bothering us every 10-20 seconds not even giving us a chance to get out of a locker or from under a bed. By the way you'd better not waste your time hiding in lockers.

The alien randomly moves within habitat and enters a vent every several minutes giving us approximately 30 seconds to do what we want. However, a noisy sound (a creaking door, alarm, explosion, shots fired etc)will immediately attract his attention.

- The alien moves within habitat around our heroine. This habitat shifts following Amanda with a delay with exception of scripted events.
- If the alien enters the room where we are hiding in a locker one of the random scripts will be triggered. Either he tries to sniff us out or just walks around and leaves.
- Upon leaving a room the alien can randomly turn back and search it again.
- After having searched a room a passive mode triggers meaning that the alien won't be checking out this room for about 5 seconds (it depends on a difficulty level and kinda random).
- If a player was hiding not in a locker but,say, under a bed then it would take more time for the alien to come back. Probably it's a bonus for taking a risk.
- If a player is hiding in a locker the alien will be walking around sometimes hitting items in the room. However if a player is not hiding in a locker the alien will just take a quick look around and leave. It also depends on a room's size.
- If a player has moved too far away from habitat but he is still within proximity of the zone where the alien can stalk us in, the alien can move fast towards a player and his habitat shifts to a player too.
-There are scripted locations in game where the alien come out and hunt you only in case you make a lot of noise.For example,locations where you need to repair a lift. If we do everything quietly the alien't won't bother us at all but,say, the moment you throw a noisemaker at a group of humans he gets to them and rips them apart and after that he will be "patroling" this location.
- the less safe the place you hide in, the more time it takes the alien to come back

PS Many thanks to VALERYN for providing valuable insight into the nature of the alien's AI ;-))