The new space Alan finds himself in is simply too large for the limited range of the flashlight. The floor has a thick layer of dust that prevents any of its details from being discernible, but the area right around the fallen door has been somewhat cleared, revealing a complicated pattern on the floor; possibly a mural of some kind.
Other than his flashlight, the only sources of light Alan can see in the room come from the doorway by which he just entered and a dim glow that can be faintly seen some distance into the darkness. The glow is seemingly obscured by the dust suspended in the air, making it difficult to discern any details from such a distance.
The walls near the door are simple metal, not decorated but also surprisingly not corroded, unlike the other side. Tracing along the walls, watching his step, he finds over a dozen doors in the hour it takes him to make a circuit. However, unlike the first door he entered, all of these doors lack handles and appear to be hydraulic or mechanically driven doors. All except one, which he finds last thanks to the direction he walked.
This door, fortunately, is in much better condition than the one he entered by and only needs a little bit of extra force to slowly swing open. The interior is quickly revealed to be the living quarters of someone, possibly a worker who lived here. It's not lavishly decorated, but it's not impoverished either. Unfortunately for the former occupant, it seems to also be their final resting place; a skeleton lays on the bed in a simple red robe, arms crossed over its body.
A quick search through the room shows that most of the supplies weren't made to last; simple contact causes them to disintegrate. The furniture and books seem to have held up better, likely due to far superior materials, but are beginning to decay as well. The books, although written in some strange language that doesn't seem to be related to any Alan knows, are clearly made of some artificial material, perhaps explaining why they could survive so long, but the ink in most of them has blurred into smudges. Books that can't be read tend to have limited uses.
Thanks to most of the contents being illegible, there are only two books that seem intact enough to draw attention to the contents. One seems to be some sort of compendium with images of various things, including the grass and mushrooms he collected. The other is handwritten, making its survival even more surprising. Alan guesses it might be a logbook or journal. What makes it valuable are the several maps, which while hand drawn, seem to be the work of a skilled cartographer. One seems like it maps out the cave and this apparently very large complex, while another seems to map out the forest above with two other spots that appear to be exits from this complex.
Following the map, he finds the door that leads to the other two exits. With a thorough examination it becomes clear to him that even with the apparent age of the facility, the locking mechanisms have managed to hold strong. Without any tools to use, there's no chance of getting any further with this approach.
Not having any other clear option, Alan starts to move towards the glow emitting from the center of the room. As he gets closer and closer, he realizes the light is being seen from an angle and is nearly eye level with him. With another few steps, a white metal platform covered in densely packed lines like the traces of a circuit board comes into the range of his flashlight. Ascending the stairs at the edge of the platform, he approaches the spot where the light is and stoops down to examine it with his flashlight. It appears to be some glass like material, through which can be seen a very dense grid of red lights, with no clear purpose or function. Placing his hand on the glass begets no reaction, an outcome repeated through all of his other experimentation.
Finally, not having seen any other thing interesting about it, he stands up once more and decides to stand on it. After all, this looks similar to the scanners from a certain historical drama he quite likes. As soon as he completely steps on top of the grid, there's a sudden reaction. The lights in the room come on, revealing a large, shiny white metal chamber with just the doors he had discovered. Another moment passes, and the thick layer of dust on the ground begins to rise into the air and transform into tiny light wisps, which quickly fade away.
The newly cleaned floor reveals the same dense, vaguely circuitry like traces found on the platform. However, mixed in with the more technological portions were what appeared to be 'magic circles'; large concentric circular traces containing sometimes seemingly random geometric patterns and even what appear to be characters of some language.
Other than the platform he currently stands on, there are four more platforms aligned with the corners of the room, making a large 'X' centered on his platform. The traces similarly run up the sides of each of these platforms, connecting everything for some unknown purpose. After the lights come on, the deep thrumming sound of machinery starting up can be faintly heard, then nothing else for nearly thirty seconds.
Alan steps off the light grid, and as soon as he does, a feminine voice suddenly starts speaking in an unknown language. Whirling around in surprise, Alan sees no one and quickly identifies that the voice seems to be artificially produced, rather than originating from someone. Unfortunately, it's some very strange sounding noises, possibly a language. It doesn't sound like any of the 3 Imperial Languages, so he's lost as to what it might be saying. Experimentally, he steps back onto the light grid.
As he does, the traces on the ground suddenly light up and start glowing with a faint red color. At the same time, Alan feels a sudden pain right between his eyebrows, as strong as what he imagined being shot would feel like. He drops to his knees, grasping his forehead and groaning in pain. But then it's gone, almost as quickly as it came on.
"Scan comple-e-e-ete. Common Langsssssshhh knowledge install." Came the voice once more, as the traces go dark. To Alan's surprise, although it was still in the same previously unknown language, he could understand it. But more importantly, there appears to be something wrong with the system. Although the meaning is clear enough, it sounds like the voice's software or hardware is damaged.
"Greeteegs. Welcome to KZZZZT-ar Entry Hall 665."
"This is an automated messsssss-. Pursssss-KCCCHT-Imperial Decree AE10-TSSSSS-4-4355, E-krrr-ar is currently closed to outside-ide-ide-ider. If you are-ZZZZT-der, you are hereby ordered to leav-eve-eve-eve-eve-mediately, under penalty of death. All natives... re...por...t... to...."
The voice then goes silent, and no matter how Alan calls or tries to interact with the platforms, there's no further response. As soon as the pain has subsided enough for him to think clearly, he realizes he is aware of a complicated language script in his head. Alan already considered himself skilled for knowing nearly 2,500 of the 5,000 common use characters in Imperial Hanyin, but that doesn't even hold a candle to this script.
While a count is impractical, especially with a light lingering headache, he's sure there must be at least a million characters, each with a unique meaning and unique shape. The facility suddenly trembles a little, like a weak earthquake, before settling down. Concerned with the tremor and wanting to get out, Alan heads to the various doors.
However, despite the facility being turned on, the doors still won't open no matter what he does, and the tremors have been slowly increasing in frequency the whole time. Left with no other choice, he heads back to the only place that might give him a lead. Looking through the handwritten book of the attendant, it turns out that it was indeed a personal journal. The attendant was assigned here to welcome people entering the Eden 'Star' from other 'Stars'. She had the job of confirming that no one entered this Star without being properly processed.
Reading further, it appears the forest planted above is specially designed to catch people who don't land in the appropriate area; both smugglers and the ignorant. Had he been 'devoured' by the trees, he would have wound up in the facility's jail and processed. However, being placed in the jail of a facility that's not even functioning only to slowly starve to death might be worse than being killed quickly by man-eating trees. Other than a few passages complaining about people coming through and the boring post, most of the first three quarters of the book is illegible.
Once Alan manages to get far enough, though, the entries start to become more legible. Apparently one of the 'Lord's had betrayed the other 'Lord's, and caused a problem with the world to appear long before she was born. The problem was becoming enough that a 'War in Heaven' was starting, hence why the facility was being decommissioned. Unfortunately for the attendant, that meant she was to destroy the landing pads, decommission the facility, and end her own life. According to the map, the two areas of stone that survived as campsites were originally landing pads, before the years took their toll on them.
Unfortunately, most of the material simply isn't that useful. The few areas that look like they might have contained useful information were erased or marked over so they couldn't be read. There was unfortunately nothing that could be used to open the other doors. Finished with the journal, Alan places it in his pack and begins to look through the only other surviving book. As he thought, it is indeed a compendium of resources, as the title of the book clearly states as much.
As he begins to open it to quickly skim through just in case, another tremor starts to rock the place, much stronger and lasting much longer than the rest. After a moment, a loud whining noise begins to be emitted on and off. Although not like any sirens he's used to, this certainly seems to be an alarm. Stuffing the book in his pack, he quickly runs out into the main room, right as the still unseen speakers crackle and hiss. After several seconds, the voice returns.
"Warniiiiiii-. Line of Exile detec-ec-ected. KK-op of Blood of Exile disco-ov-ov-ov-Tcch-arning. Ssshh-665 breached. Activ-Kzzzt-gency teleportation arr-arr-arr-array. Sta-ZCCCHT-n platform to lea-ea-ea-eave." The voice then changes to nothing but random buzzing noises as the mechanism appears to fail. As Alan runs for the central platform, another tremor starts up. With difficultly and only stumbling thrice, he manages to make it to the central platform.
As he enters the space in the middle of the platform, the traces on the floor light up. Only, instead of the dim red glow from before, they're almost oozing an inky blackness upwards, the weird substance dotted by tiny pinpricks of white light. As it rises, it dissipates into nothingness, giving the appearance of a dissolving starry sky. Small particles of white light coalesce around the central platform, as a loud banging noise is suddenly heard from one of the massive doors Alan couldn't use.
Terrified by what could be making that sound, he squats down, hoping to not be seen before this process is over. As the light motes get thicker and thicker, forming into a funnel of lights that can barely be seen through, the banging reaches its apex with one final hit that sends the door flying. Behind the door is a humanoid shape shrouded in shadows, with only an eerie red crescent and two red circles to serve as a face.
"I SMELL DELICIOUS BLOOD!" Came a discordant voice, sounding as if it were made by rubbing shards of glass against a chalkboard. It lunges itself forward, reaching towards Alan in the center of the platform. "TONIGHT, I FEA-"
Too bad for the being, it came too late. Instead of laying its hand on Alan, the shadowy being lost an arm to the vortex of light motes, as the teleportation is completed. The arm itself disintegrates into nothingness as the shadowy being howls in agony.
What came next was a shock to Alan, though. He expected a nice, calm, instant movement to the destination, thanks to what he knew of teleportation from fictional works. Instead, he was flung bodily through an unstable spatial corridor.
From wherever he entered this space from, Alan felt himself being hurled very quickly through the pitch blackness here. As the torn apart space rips at his body like blades, he could only count himself lucky that something was keeping them from aiming directly at him, barely preserving his body in one piece. Still, that didn't stop him from cursing his fate or that bastard Ye Jin another few dozen times.
Perhaps it suddenly appeared without him noticing, or perhaps he lost conscious for a moment, but Alan notices a very bright light appear head of him, which he's approaching rapidly. His blood soaked body continues to move forward until it enters the light as exsanguination causes him to lose consciousness.