Our universe is unstable. Even the slightest perturbation will lead to expanding or shrinking.
The year is 2031; the world remains shackled by a new virus that has been erupting for the past 10 years now, climaxing in an inevitable war between the USA, China, and Russia in the struggle for power and monopoly over medicine and resources to repel the ongoing pandemic. The conflict escalated into the biggest war in modern history, causing over half of the planet to be covered in flames.
Wide-scale fires as wide as football pitches and as tall as the highest skyscraper on Earth and the use of nukes and intergalactic weapons disrupted the stability of the galaxy itself, causing our universe to contract. This contraction event decimated the universe as we know it and made Earth uninhabitable. Civilization slowly started to crumble, nations fell to give way to a large number of different factions headed by wealthy individuals from the old world. Strange things also started to happen. The radiation from the contraction event started changing the biology of some people, not long after this event human beings also made first contact with aliens.
In the year 2049 we also discovered a new habitable planet named 'Bruna 8' in the far corner of our observable galaxy; it seems that while the contraction event destroyed most of the galaxy as we know it, it also pulled other new planets into our galaxy, revealing to us other planets, stars and other intelligent beings that the human race have never seen before.
After 'Bruna 8' was discovered, the wealthy started sending the general population up there to explore the planet for resources and make sure it's safe before they themselves left Earth to go to Bruna 8. The people who were sent up to the Bruna 8 were known as the 'disposables', named after their survival rate from these expeditions to Bruna 8. What the disposables discovered on Bruna 8 was both dark and alarming.
Originally thought to be an empty but resource-rich planet turned out to be a deserted and long-abandoned planet that was inhabited by highly intelligent species. Humanity had already encountered aliens after the contraction event in 2031 but what they saw on Bruna 8 indicated a highly intelligent species that were hundreds of years ahead of their own. Most of the architecture on Bruna 8 did not survive but a giant 5000 foot grey tower stood alone, with an arena on top of it.
Those back on Earth was in awe at this discovery, Bruna 8 could potentially hold advanced alien technology as well as valuable resources, the wealthy scrambled to send the disposables up to Bruna 8 to capture resources for them in a literal land-grab. This lasted for months and months, with land on Bruna 8 being captured and recaptured by different faction leaders.
In the end, the agreement was made between all the faction leaders, instead of engaging in constant battle over the coveted land, they will settle the distribution of resources of Bruna 8 through battle tournaments hosted in the only remaining architecture left on the planet.
The rules were simple, the faction leaders could recruit anyone or anything (non-humans) they want to form a team of 3, these 3 person teams will then battle with another team representing another faction, the winning team from each tournament will win these keys.
These keys could be used to unlock resources that was discovered on Bruna 8, these included highly advanced weapons as well as armor and many other untold treasures. It was decided that this was the best way to fairly allocate the resources on the planet instead of a free-for-all battle between all the factions.
Faction leaders then began to scout and recruit from earth those who are best suited for combat on Bruna 8, many mutated human variants and non-humans that were previously considered useless and relegated to the bottom of society suddenly became valuable for their combat potential.