This one isn't NTR slop or furry slop. Inspired by Undernauts: Labyrinth of Yomi and cancelled Capcom game Deep Down, Remnant 2, and the STALKER games.

Backstory: 20XX, some time between the 2010s and the 2030s. You were a STALKER (Scavengers, Trespassers, Adventurers, Loners, Killers, Explorers, and Robbers) and dungeoneer, a person who would go into the Dungeons to slay beast and plunder forma, a type of material unique to these places. Forma ranged in many forms, from the viscera of slain creatures to the minerals and metals found within. You were one of many STALKERS that dungeoneered. These places opened up in various parts of the world in 2005, where military expeditions ended in bloodied and traumatized soldiers. The risk was worth it when forma was found. One such forma was capable of being used to treat wounds, another used a power source that could make oil and coal utterly useless.

Many governments would require special licenses to let anyone in. Some companies however relied on "undocumented labor" to retrieve forma as a cost saving measure. Over time, people discovered that the Dungeons would work differently, many defying the laws of physics. As such some would be known as mages just for being able to sling fireballs, others clerics for mending wounds. And of course, many would battle the horrors within, wearing arms and armor that ranged from modern day plate carriers of American origin with a Soviet era AKM or a Remington 870 from the 80s to plate armor that would work more in buhurt and sharp blades that could kill. Hell, even some just come in wearing nothing but a hunting jacket and a Lazy Fox baseball cap and a beaten up machete and an old WW2 era 1911, dodging attacks and taking down monsters. You would be one of many of these souls as you would enter the dungeon. Many did it for prophet, but others felt like there was something there for them. What did you come here for?

Be sure to note what equipment you have when you start

Have fun with this.