Ouroboros

Ouroboros is a 2.1 upcoming Extreme Demon mega-collaboration hosted by Viprin and set to be verified by Knobbelboy, who has achived a record of 76% on the level as of May 4, 2019. It is a purple, orange, and red hell themed level with a dragon boss fight at the end.

History
Soon after Subsonic was verified by Combined, Viprin said he had about sixteen more mega-collaborations planned, two of which were set to be Extreme Demons. On September 10, 2017, Viprin released Digital Descent, one of the Extreme Demons he was talking about (also verified by Combined). Later, on October 1, Viprin uploaded the first preview for this level.

On March 2, 2019, Knobbelboy began streaming progress on Ouroboros and got a record of 29%. As he practiced, several creators were finishing their parts in the level. Two days later on March 4, ChaSe97 released a video showcasing his part in the level. In the video description, he stated that his part uses around 37,000 objects because of all the details he put into it. The next day, however, he released a second video showcasing his second part in the level, which consisted of a fast-paced dragon boss fight and uses roughly 40,000 objects. On the same day, Osiris released a video showcasing his own part in the level. In the video description, he explained that the background is based off a city in flames destroyed by a dragon.

Four days later on March 9, Knobbelboy achieved an incredible 49%. In the video description, he predicted that it will definitely be harder than Plasma Pulse Finale in its current state. After a long absence on March 24, he achieved runs of 65-100% and 52-93%. In the video description, he stated that he still doesn't think it is harder than Plasma Pulse Finale, but still believes it is at least as hard as Yatagarasu.

The next day on March 25, Darwin uploaded a video showcasing his updated part in the level, which contained some new pulses and a few minor details. After a long period of inactivity, on May 4, Knobbelboy achieved a new record of 67%.

Gameplay

 * 0-4% (AbstractDark): The level starts with AbstractDark's part holding a Low Detail Mode key right before the gameplay begins. A normal speed cube is used and a dash orb, two green jump orbs, and yet another dash orb are used to get the level started. Shortly after, the player enters a robot segment and keeps going with the mostly orb-based gameplay. Timing also plays a big part in this robot segment as the speed has not yet fully built up yet. Just before the next part, a double speed portal is passed to build up the difficulty for the next part.
 * 5-12% (Terron): The robot goes back to cube form, now mini, and a more fast-paced gameplay section approaches. Many orbs start off the part which then comes at the player with a short straight fly. Then comes a narrow spider followed up by a quick mini wave transitioning into a cube, picking up the speed even more to triple speed. A few more orb jumps follow, and then a quick UFO segment into another cube quickly followed up by a wave switching size mid-gameplay. Finishing Terron's part is a long double speed ship sequence with a few gravity switches and size/speed changes as well as tight gameplay overall.
 * 13-22% (Rustam + TrusTa): The gameplay transitions from Terron's part to Rustam's via a quick cube section and the screen turning white for a second. The gameplay starts off with a cube avoiding several arms while transforming into a ball. After that is a wave requiring a single click, and then a small cube maze. This maze is followed up by a short ball segment into another single tap wave. This wave then comes to a more drawn out ball section with lots of timings, and then a long wave segment with both gravity portals and size portals involved. Finally, there is a cube section where the main boss of the level, the dragon "Ouroboros", is shown before an auto segment takes the player to the next creator's part.
 * 23-30% (Darwin): The speed goes back to double and starts with more tricky jump orb gameplay as a cube, with art resembling a volcano in the background visible through the whole part. The first cube section is followed up by a short but difficult ship sequence, and then back to a cube, although now at triple speed and with even more orbs to hit. Then, right before the second half begins, an extremely tight mini wave section emerges, similar to those found in Zaphkiel. A robot segment is next and contains many timed jumps to pass before it goes to a cube, and then back to robot shortly after. The part finishes with another incredibly narrow wave segment at normal size and quadruple speed before the player is rewarded with a quick auto section and a single jump to keep going.
 * 31-36% (TheDevon): This part focuses more on decoration than art like most previous parts have. The entire part is played in ship form, starting with a dual mini ship in half speed. A monster opens its mouth in order to let the player through. Rocks then float up from the ground as the player approaches another two monsters letting the player pass. Before Devon's name and icon show up, the speed goes to normal and flashing lights appear in the background. Yet another monster opens its mouth, and the ship then goes single and to double speed for the final seconds of the part. More speed changes appear to the beat of the song as the ground and ceiling begin to flow, and a text over a black background finishes up the part reading "!WATCH OUT!".
 * 37-41% (Ferdefunky): 
 * 42-47% (DesTicY): 
 * 48-52% (ChaSe97 I): 
 * 53-57% (Viprin): At the very beginning of the second preview, we saw that Viprin's part ends with some frustrating cube gameplay, followed quickly with some orb spam.
 * 58-61% (G4lvatron + TrusTa): 
 * 61-66% (OSIRIS): 
 * 67-78% (Loserchik67): 
 * 79-100% (ChaSe97 II): A very difficult dragon bossfight.

Trivia

 * It is the first Viprin mega-collaboration that is set to be verified by Knobbelboy.
 * According to TrusTa himself, this level will be harder than Yatagarasu, despite not being set to be #1 on the Official Geometry Dash Demon List.
 * It was originally planned as a spiritual sequel to Yatagarasu.
 * In mythology, the Ouroboros is an ancient symbol depicting a serpent or a dragon eating its own tail.