On a research lab for one of the Jupiter moons, post-Hell invasion and recovery, some demons
have been captured by soldiers and scientists who are working together to find out as many
things about them as possible, and help find better ways to defeat them. Everything was
going well at the research lab, however, one fateful day would change everything...

It was the day a Cyberdemon, potentially the most lethal demon ever seen by a human, managed
to break free and run amok in the lab, destroying everything and everyone. An emergency
squad of marines were dispatched to take care of it, but they were no match for it. The
demon was too strong, the corridors too cramped, and their forces underpowered and confused.
It was a nightmare...

However, before he was annihilated by the beast one marine did manage to wound the demon.
The Cyberdemon, possibly about to encounter reinforcements and hurt, fled deeper into the
complex to hide until he could summon help from beyond. But just like he turned to bad luck
for the lab, the lab turned bad luck for him.

Inside the particular room the demon blasted his way into, was an experiment in using
optical illusions for combat and security. A large machine and control computer powered this
bizarre device, known only as the "Illuso-pit" by outsiders to the project. As the base was
being evacuated, nobody thought to deactivate it in the chaos, and whoever did was very
intelligent in not doing so.

Just as the Cyberdemon ran into the room, he fell right into the trap! The hurt beast had
fallen right into it, and was trapped for good. The Illuso-pit was deep and very difficult
for even such a tall monster to escape from. But no, there had to be a way, the demon just
wouldn't give up. He sat there in the pit, pondering...

It was about this time a teleporter at the other end of the room, the teleporter flickered
to life as a marine teleported into the room to continue his guard duty. Poor guy was stuck
on the shitter the whole time, and had no clue what all had just happened. He was about to
get an idea though, as it turned out the room was completely empty. Even weirder, the door
was blown and the Illuso-pit device had been left on... securing the nearest weapon besides
his pistol, a mysterious Blast Field Gun and extra ammo in the computer area nearby, the
marine goes in to investigate...

That marine is you. Good hunting.