The Catacombs
If there are things worth more than anything else to Humanity, they are entertainment, and money. No matter their origin.
And thus, the smash-hit TV gameshow, "The Catacombs", was born, with dozens of divisions worldwide. Having made vastly more money, and having more viewers then any other show, ever.
The premise is quite simple:
1: Find an abandoned military complex, renovate it and fill it with weapons, and other tools useful in a survival situation.
2: Add, "failed", and previously secret biological experiments left over from World War II
3: Add violent prison inmates that were sentenced to death.
4: Add cameras
Excessively violents scenes are edited out beforehand, although live, unedited footage is available, usually in movie theaters, almost completely eliminating other horror/slasher screenings.
The vast majority of, "experiments", are kept locked in pens 12 hours of the day, during which the inmates are free to do whatever they like, and will only have to worry about coming into contact with the few stragglers that are only a threat to those with their guard down.
The harming of other, "contestants", is not allowed however.
During these off periods, viewers are able to vote for who among the contestants they feel is best for whatever reason, and depending on how many votes they get, they're given bonuses. Bonuses could be almost anything, from an extra meal, to weapons or ammunition, to batteries.
Some things have not gone according to plan however...
A few of the experiments were genetically viable for reproduction, and so they did. Eventually it became impossible for individuals to stand a chance, and so it evolved into a team game, groups of 3-4.
At the same time, crime rates dropped rapidly for fear of participating in the game.
Teams need more people, but less people are available, a problem obviously, then they found a fix...
Instead of being restricted to dangerous convicts, who were then put into small, more sustainable divisions, they began to allow civilian participation. Anyone over 18 with no drugs in their system is allowed to participate to be assigned to a team, or entire teams can put their names on the roster.
To make up for the general population's overall lack of... toughness compared to the convicts, they are allowed to bring in a single backpack filled with almost anything in with them. This proved to be too great an advantage however, and then the monster population began to decline... Again they found a fix, this time in repealing one of the games' few rules.
Teams are now allowed to attack one another.
Alliances can be made, but only one a per-day basis. Alliances have to be renewed prior to the start of the next night to be considered official. Breaking the truce of an official alliance is a pretty major offense, anyone who does is singled out for attack by the monsters for anywhere from 1-3 days, depending on the manner they break the truce in. They are of course excused from this if the offended team forgives them.
If one wants to switch teams, they're also allowed to do that, but only once, ever. Once a team reaches it's 4 person limit, no more people can transfer to that team obviously.
Will you survive the days, weeks, maybe even months to be the last team alive? Tortured by the horrific sounds of the creatures prowling the corridors, dimmed to simulate night? Your only external contact as hidden cameras, scattered TV screens showing game notifications, chutes giving you your prize for the day based on your votes, and the voice that lets everyone know when another team has fallen, and how many remain?
Get it now? Good. Just pass me your forms and you can head in. Don't forget how dangerous this is though, if you want to back out this is your last chance, and you have until night to decide, that's when the games officially start, which also means no killing until then.
