[Nimrod]

Way back in on May 30, 2014 the early beta of The Forest game was released.
I remember seeing some early lets play videos of those early versions and somewhere along the way there was discussion that the randomly generated man-eating humans that were the initial antagonists the player encounters had additional physical modifiers added so that they did not all look the same.

One such parameter had supposedly been an AI breast size modifier. There was some speculation in the support forums that this had been an April fools joke. It was also very difficult to prove as there did not appear to be noticeable changes in the shape of any of the native, of either gender.
Also, rarely were there enough female human natives around to compare from one to another.

After a while and after some additional "tribes" and more "types" of natives were added did something start to appear. In the game it was possible to interact with the native AI system and the player could gently coax more consistency in interaction and the native types they encountered.

They were consistently hostile, but not always deadly. In a few rare cases the system would glitch and a few natives would "surrender" or simply just not attack and just let the player come right up to them. This allowed for better comparison of the BE modifier if it were.

Although the change was subtle there were a few instances where the same base model female would appear at the same time but with different chest sizes. There was a modifier at work.

The attached image roughly follows the modifications of the female AI cannibals of the game:
Var 01-02: Some of the earliest females, two basic looks and the same generic body.
Var 02 (special): A glitched female in an early higher texture map, she is submissive.
Var 02b: The glitched female could be eventually provoked showing the AI was active.
Var 02b-2: Two generic females but just after the breast modifier was announced. [April 2016]
Var 02b-3: Rare event, dual attacks by the same base model female with different busts.
Var 03: Shortly after more detail was added but the breast modifier possibly OFF [late 2016 or early 2017] and submissive which was very rare.
Var 04: Much later, even more detail with the modifier back ON, about the largest they got.


In the end the very existence of the breast size modifier was debated and it is still hard to compare sizes as the human females of the game now all hover close to the same size -however there is variation that was not there at first.
In the end it was concluded that there was some manner of breast size modifier but not long after it was introduced the parameters were adjusted such that the females of the game tended to all sport something similar to Var 01 (the original size) with the rare times they might spawn with something noticeably smaller or larger to add just a bit more variety.

Var 04 in that image was from just around the time of the full release in 2018 and was a screen cap from a player who had been trying to find "the best looking native" on the island. He even said that this was probably the "most boobie one" he had run into. The fact that there is one of the deformed 'Virginia' mutants nearby, in the snow, up in the mountains of the game is a clue to just how long he had been playing by this point.

I would have to say that just after the breast modifier (if that is even what it was) had been activated, see Var 02b-2 sample, that was the near maximum size ever in the game. There were some adjustments in size through 2016 and it appears that the modifier was restrained sometime in early 2017.

Some lengthy digging around has turned up some supposed screen captures from 2016 of very busty random natives but confirming that they had not been digitally edited is difficult. A follow-up may be needed.

[Nimrod]

It took a bit of digging and some frame by frame review but The Forest BE "mystery" appears to be solved, and was unfortunately a thing of the past version of the game around mid to late 2016.

Just to mention it here, the historical facts so far are:

A. About April of 2016 in the routine beta testing bug and feature fix list a single line item stated that a "breast size modifier" (BSM) had been implemented - many early players speculated that it was an April Fools joke and with few female model types and rare multiple encounters it was very difficult to even refute on way or another.

B. Through the rest of 2016 as more model types and AI behavior were added there did start to appear some possibility that there was a BSM at work. A few rare times the same randomly generated AI female would spawn more than one time and it did appear that the a BSM was giving them different chests.

C. Possibly to improve realism or reduce the number of times larger breasts clipped through the arms, bodies, or clothing of natives the BSM appears to have been removed or greatly limited in releases starting in early 2017 to the final release in 2018.

D. Over the years a few clips and frames of female encounters have been posted showing surprisingly chesty natives, much larger than the default female model but these often appeared to be photo edits or other such things and most were from game play well after the BSM was said to be active or even in the game.

That is until I happened upon the streaming clip of a Var 04 female native captured in late 2016 which had a single frame of her attack where she sported (for the game) a massive chest. The promo still looked so fake due to the size simply because it was so much larger than anything normally in game. However the posting date did sit at just the right point in time when there were the most female model types and the BSM was at full power. I was able to track down the stream and here is what is happening.

The surprising news is that the still promotional image is real. (first image in the attachment here) I was able to frame-by-frame find the exact moment that the screen capture was taken. It was not a brief model glitch and her size persists through her attack as can been seen a few frames latter (3rd still). That is a clue as to what is happening here.

When reviewing frame-by-frame the model leading up to the attack and ironic death of the player there were some very interesting size changes going on:

1. - A very busty Var 04 female in generic stance - the BSM appears close to the maximum setting. It was during late 2016, it was obvious when the BSM had or had not endowed a female.
2. - Var 04 about to strike at player - note the placement, size, and fullness of breasts.
3. - Var 04 was just struck by the player's axe (note blood spray near head) - note breast size in this frame.
4. - Var 04 in the very next frame - now with blood texture map painted over torso - it is difficult to see at this angle but her chest just expanded by about a cup size and is most apparent in her left breast.
5. - Var 04 just after the model resets and now more aggressive (her chest expands a second time at the start of this new sequence) attempts a second attack. Her chest is noticeable fuller. The super busty promo still image is taken just a few frames after this one.
6. - Var 04 female receiving a second blow of the axe. Again, the breasts nearly fill the width of her torso and have an overall fullness not seen anywhere in the game.
7. - Var 04 just after landing a killing blow to the player and returning the generic stance. Notice the deflation of the chest back toward where she was in image 1, still large but nothing close to the attack sequence sizes.

Note: This entire attack sequence lasts about 3-4 seconds from the player's first strike to when they are brought down by Var 04's third hit. The BE happens very fast and often over just 1 or 2 frames.

What is going on here...?

The already large model goes through 2 BE phases during this very brief battle only to revert to the near Max. BSM size.

It has to do with four factors all interacting at the same time in this rare stream capture. This is the perfect combination that resulted in probably the largest chest size on any female in The Forest that you will ever see. (without custom mods)

First - the player was lucky enough to encounter a Var 04 female which appears to be the most busty base model at a time when the BSM was fully active and she happened to spawn with about the largest chest possible. So, the most chesty model gets the biggest random boost right from the start. Realize that the BSM only gave about a +1 to -1 cup size.

Second - and this is a bit more technical and has to do with the different motion and attack sequences - but suffice to say that the natives act as a sequence of preset poses, stances, emotes, and attacks all strung together by the AI. It just so happens that the player encounters a female just about to shift into high aggression mode, which oddly affected breast size...

Third - when shifting from one mode to another the character mesh responds to that mode's parameters some of which include things like invisible hit boxes, render detail, etc. When the female is hit and shifted modes (when she got the blood texture) there was a slight shift in the control points and her boob mesh moved to fill it.

This is sometimes called a modeling error, however it is often just an interaction when the character mesh has to shift to accommodate a new mode. This is exactly what was happening to the Widow-maker character in early releases of Overwatch when her buttocks and other body parts would expand when she activated her special ability.

Fourth - now in an attack mode the Var 04 aggressive model returned momentarily to the generic stance as the AI determined what to do next. One or two frames later the AI shifts into full attack and there is a second direct attack (the promotional still) and this elicits yet another mesh shift. This time it appears to be a hit box expansion or possibly skeletal deformation error as the breasts grow in a single frame to massive (for the game) and remain so through the entire final strikes.

Lastly - as the player receives the final blows and starts to slump to the ground the AI shift the Var 04 back toward her general aggressive mode. She quickly losses her massive bust line and shrinks to something close to her starting Max. BSM size, but not entirely.

It took me a moment to realize why the model did not return to the pre-fight size and then it occurred to me that there were other players in that session standing behind the downed player. The AI had not returned the settings fully at there were still threats nearby and the Var 04 was now injured. This paints a totally different picture as to what the AI engine and the BSM were doing and probably why it was ultimately removed or limited.

So what does this all mean?

Well, this promotional still is the largest bust you will probably see on a female character in The Forest without custom mods and it is not possible due to the hobbling or removal of the BSM.

This massive bust was a rare combination of the right base model, at near max BSM, a combination of minor model errors dependent on the action mode of the model, and a player who just happened to be standing at the right place and close enough to record both breast expansions in order to capture and be killed by the largest boobs in The Forest.

What a way to go...