What's on WIkki basically comes from the game.
The series is set in the near future, where aliens known collectively as Votans have come to Earth seeking a new home after their star system was destroyed in a stellar collision. The Votans had thought Earth was uninhabited, but upon their arrival in 2013 discover that humans are living on the planet, who respond to them with hostility and suspicion.
A limited number of Votans are allowed to settle in a colony in Brazil, and eventually two other colonies, but millions of Votans remained in hypersleep aboard their ships in orbit as negotiations dragged on with Earth governments for full-scale settlement.
Tensions rose for ten years, but the Votan and human governments were on the verge of negotiating a peaceful settlement, when in 2023 the Votan ambassador to the United Nations was assassinated by a disgruntled human supremacist on live television outside of the United Nations Headquarters in New York City. This sparked a disastrous global conflict between humans and the aliens known as the "Pale Wars".
The wars tore apart the planet for seven years, until their culmination in 2030 in the apocalyptic "Arkfall" event, when the Ark fleet in orbit mysteriously exploded. The aliens think a rogue human commander was responsible, while humans suspect it was an alien weapons experiment gone awry. Millions of Votans died in hypersleep. During the Arkfall, destroyed Arks rained down on Earth and accidentally released terraformer technology.
While the Votans had intended to use their terraforming technology in a carefully planned manner, the Arkfall haphazardly unleashed chaotic and radical changes to the biosphere and even the geology of Earth, making the planet dangerous to both humans and the aliens. The earth was scorched, chasms opened in the ground, new mountain ranges were raised, and the surface of the planet was covered with dust and debris.
Animal and plant species from the Votan star system were introduced to Earth, and both native and alien animal species were horribly mutated by the uncontrolled terraformer technology, creating bizarre and dangerous hybrids and new species.
Within a few months, the Pale Wars wound down as both sides had fought to the point of mutual exhaustion, and a ceasefire was declared. Few organized governments remained for either the humans or the aliens, and both sides factionalized as their members began looking out for themselves. In several areas, local human and Votan militias began to band together when they realized that they had to cooperate if they hoped to survive on this new, almost alien planet.
The debris from the destroyed Ark fleet now forms an artificial "Ark belt" in Earth orbit, which periodically rains down in small scale "Arkfalls", which present a hazard for survivors on the surface, but also provide valuable opportunities to salvage advanced technology aboard the Arks.