AI Camouflage

Hiding actually works. What you wear, where you stand, how you move and what you have just done all decide how easily enemy soldiers notice you, and the AI can no longer look straight through grass, bushes, walls or hills.

Clothing that matches the ground

Every uniform, vest, helmet and backpack has a rating for how well it hides you on each kind of ground: woodland, jungle, savanna, desert, snow, urban, rock and underwater. The game compares what you are wearing with the ground under your feet. You can see each item's ratings in the ACE Arsenal.

Clothing that matches the ground makes you harder to spot, and clothing that clashes with it makes you easier to spot. It is a sliding scale, not all or nothing: partly matching kit gives partial credit.
The uniform counts for most of it (about two thirds). The vest, backpack and helmet count for less, in that order. Only what you actually wear counts, so a woodland uniform with a desert vest hides you less than a full woodland outfit. An item with no rating counts as no match at all.
A full-body ghillie suit decides everything on its own, and the rest of your outfit is ignored. Only the uniform decides whether you count as a ghillie: a ghillie helmet, vest or backpack over an ordinary uniform only adds its ratings to the mix. A ghillie is never a complete mismatch: it always breaks up your outline a little, even on the wrong ground.
Dark gear helps in the dark on any ground, more so the darker the night.
Bright or civilian clothing stands out on top of that, and a hi-vis vest gives you away even over camouflage clothing.
Wearing no uniform at all leaves nothing to blend in with.
Standing on a paved road, inside a building or under a roof counts as urban ground: urban gear matches it, and everything else stands out. Even a ghillie suit no longer matches there, though it still breaks up your outline a little. Dirt tracks and trails keep the ground's own match.
Water is its own kind of ground, which diving gear is made for.
Ground the game cannot classify counts as neutral: it neither helps nor hurts.

How you carry yourself

Lying prone hides you best, crouching helps, standing is the most visible.
Standing still is far better than moving. The faster you move, the easier you are to spot.
Firing gives you away for a while, then fades over roughly twenty seconds. Firing with a suppressor gives you away much less, and subsonic ammunition (slow bullets) gives you away even less than a suppressor does. Subsonic ammunition through a suppressor gives you away only slightly.
Visible tracer rounds are a giveaway that a suppressor or subsonic ammunition cannot hide, and they are much worse at night. Infrared tracers cannot be seen without night vision, so they do not add to it.
At night, light on you matters. Standing in a flashlight beam, under a lamp or next to a flare makes you much easier to spot, and so does switching on your own weapon light (an infrared light does not count, since it can't be seen without night vision), and strong light also stops you counting as deeply hidden. A flare far away or high up counts for much less than one right next to you. Standing in the dark, with no light on you at all, makes you harder to spot. None of this applies by day, indoors or under a roof.
Bushes, trees and long grass around you hide you more the denser they are. Standing on a road gives no cover from grass.
A ghillie suit crouched or prone in real cover, and staying slow, gets an extra bonus.
Regular clothing never becomes as hard to spot as a ghillie suit, no matter how good the cover.
While you are inside a vehicle none of this applies.

Quiet when you creep

Staying still or creeping makes you quieter, and crouching or going prone quieter still. Dense foliage muffles your movement. Sprinting, or a shot in the last few seconds, makes you louder for a moment. This can be turned off separately.

The AI cannot see through cover

Enemy AI used to keep an exact fix on you through solid-looking grass and bushes. Now:

Hills and walls always block their view.
Deep grass and dense bushes block it too when you are low and reasonably still. Standing up, running, or being close enough removes the protection. A ghillie suit lets you stay hidden from closer than ordinary clothing does.
An enemy group loses its lock on you when none of its members can genuinely see you. It does not drop you the instant you duck, though: if they clearly saw you a moment ago, or you are very close, they keep tracking you for a few seconds before cover can hide you again.
Night vision beats grass and bushes. An enemy soldier who has night vision switched on (not just wearing it) is not fooled by soft cover and needs less of a view of you to spot you. Walls and hills still block them.

In the arsenal

The ACE Arsenal item info panel shows how each piece of clothing or gear helps you hide. For uniforms, vests, helmets and backpacks it lists the kinds of ground the item blends into (woodland, jungle, savanna, desert, snow, urban, rock and underwater), each with a bar and a rating from Poor to Excellent. Ground types the item does not suit are left out. It also says whether the item helps in the dark (night camouflage), how much it draws attention (bright or civilian clothing) and whether it is a ghillie suit or a full-body ghillie suit. The panel shows five rows at a time, so use the page button to see the rest.

Works with LAMBS

If LAMBS Danger is running, AI will not radio your position to a unit that cannot actually see you (blocked by a wall, hill, dense cover, or deeply hidden). Nothing else about LAMBS behaviour is changed.

Settings

Everything above can be tuned or switched off under Addon Options → TF999 AI Camouflage: an overall on/off mode, how strongly clothing, stance, movement, cover and firing affect you, how far and how often the AI cover checks run (to save performance), the LAMBS option, and a testing readout that shows your own camouflage numbers on screen. See settings_users.md for the full list. This addon has no keybinds.