Currently, there are 9 official ARKs, 5 of which are canon and 4 of which are non-canon but WC accepted DLC's:
The Island, an island ARK. - Canon Paid DLC
Scorched Earth, a barren desert ARK. - Canon Paid DLC
Aberration, a malfunctioned, subterranean ARK. - Canon Paid DLC
The Center, a region-divided island ARK. - Free DLC
Ragnarok, a giant island ARK. - Free DLC
Valguero, an expansive land-locked ARK. - Free DLC
Crystal Isle, a huge fantasy driven ARK - Free DLC
Extinction Canon Paid DLC - brings survivors back to where the mysterious journey all started; Earth. What was once a lush and thriving home world is now a corrupt, hostile and desolate shell of its former self. Extinction is not an ARK but rather, an area on the corrupted earth, that house's Proto-ARKs. The forerunners of the true arks like Island and Scorched Earth. There are Many other ARK's that exist out in the ARK'verse, and most are referred to as Modded maps.
Genesis I, Canon Paid DLC - Will take your story in an all-new direction — and your skill determines your success. This time you are in a simulation, and itself isn’t perfect, you will have to find ways to fix the glitches scattered throughout the world. Master the simulation, and you can test yourself against a mysterious new boss… the likes of which ARK has never seen before. Only the toughest and smartest survivors will pass all of the simulation’s many tests. Will you be one of them?
The ARKs are space stations intended to house living organisms such as Humans, Creatures, and Plants. These ARKs were sent up prior to a global-level extinction event in which Element wiped out the Humans. The ARKs are powered by the Obelisks, and each ARK contains at least one Guardian. When a certain signal is given from the Earth through a strange Tek machine via a Specimen Implant, this causes all ARK to slowly descend onto earth, forming a giant seed that blooms over the Earth's wasteland, turning it into a blooming environment that once was before the global-level extinction event, and eventually rid the raw, corrupt Element that had overgrown over it.
Proto-ARKs can be found on Extinction and are prototype ARKs. Unlike the environments that were sent up into space, Humans and Creatures can freely enter and leave the Proto-ARKs. When entering or leaving, a de-materialization effect will occur. 3 Proto-ARKs can be found throughout Extinction, two of which are operational, Desert Dome, Snow Dome, and Crater Forest. The Crater Forest was a failed experiment. This underground forest was formerly an operational, forest-themed Proto-ARK but sunk into the ground.
The Homo Deus are beings created to watch over the ARKs. These beings can rarely resurrect any Humans. One did and created a new Homo Deus, A notable one, "The One Who Waits", who guides the survivor through The Island, Scorched Earth, and Aberration to Extinction via the use of Notes and Dossiers.
Spoiler ALERT!!! If you do not want the mysteries of the ARKs or the ending to this story spoiled, PLEASE DO NOT READ THIS! Part I: The Island in the Sky Part II: The Destruction of the Obelisks Part III: The Call of the Corruption Part IV: Extinction's Salvation Thankyou u/diamondcreeper of Reddit for the wonderful condensation of ARK's Lore. Original post the links are from: https://www.reddit.com/r/playark/comments/cmf0xa/everything_you_need_to_know_about_arks_story/