Bloodbath

Bloodbath is a very hard and very long demon created by Riot and others. It is supposedly a continuation of Cataclysm, and is followed by Aftermath.

Bloodbath is one of the hardest non-impossible demon ever created, generally said to be tied with Phobos and Sonic Wave. Riot verified this level in a livestream. It is considered, by many in the community, as the hardest possible level in Geometry Dash.

Since then, four other players have beaten Bloodbath legitimately after Riot. They are: Quasar on 4 March 2016, Surv on 31 March 2016, and SoulsTRK on 6 April 2016.

Description
This level is mostly inspired from Cataclysm, incorporating red color schemes (though it changes to grey at Evasium's part). The music starts at approximately the point where Ggb0y ended Cataclysm. It also incorporates many hard parts like flying in between close spike passages, much like the level it was supposedly based off of. Bloodbath has an intended sequel called Yatagarasu, another extremely difficult megacollab that is set to be released after the verification of Sonic Wave Infinity.

Gameplay
Weoweoteo: The level starts with the ship gameplay at the time where Ggb0y ended Cataclysm. The level fades to a brighter color scheme of black and red. If you look above, you can see a face resembling Weoweoteo's icon. A slow speed portal follows, and quickly progresses to a double speed cube, then a triple speed ship, where the music changes key from C minor to F minor.

The triple speed ship has flashing colors, and a straight 1.5 block space to fly through, gravity portals switching the gravity of the ship periodically to the beat. The space is made up of spikes held by chains.

The transition to the triple speed mini ball was a half speed fly up for a split second.

The next sequence is a triple speed mini ball with the same color scheme, and the objects flashing to the beat. At the end of the sequence, the ball goes on a yellow pad and a half-speed portal to transition to the next ship segment.

Vermillion: The next triple speed ship segment is not straight flying, but up and down. The gravity changes rapidly, with a ramp at the end, with a open space holding Vermillion's signature. Thorns and gears are used for this part, and so is the before 2.0 brick blocks and plain black ramps.

The half-speed ball after the ship requires precise timing; each tap is a note of the song, which is now a major key (E♭ major). each platform that the ball lands on is held up by chains, and is made of red bricks at the corners and black blocks with two lines in the middle. Extra spikes make the level harder, and hexagons decorate the platforms. A mirror portal flips the screen while the player is still playing, with no break to get used to the backwards orientation. After the backwards segment, styled the same way as the forwards segment, the ball is pushed into a line of portals as the music crescendos and notes go higher.

Michigun: The music stops it is hectic, fast pace and starts a more peaceful section in its original key (C minor). The level reflects that, and the speed turns to 1x speed. The hectic flashing stops, and a original cube sequence involving a triple spike, then a gravity change, occur. Torches are used in the background and they flicker. Thorns are seen on the ground again, and chains hold up the platforms. This segment is like a narrow hallway.

A 1.5 block "narrow hallway" ship sequence starts right after the last triple spike. Spikes make up the ground and the top.

There is a ball sequence after the ship similar to the cube before, making the ball flip through a one-block space made of two spikes to reach the platform on the top.

A UFO sequence is next, similar to the ship, and the trick is to tap when a player is about to hit a spike. This gameplay makes this part harder than the rest.

Another cube sequence follows, with more triple spikes, styled the exact same way. The music is still playing it's peaceful, flat-key melody.

A one-space wave follows, and one can see the flashing red MICHIGUN in the right corner. This is the end of the "hallway".

Evasium:

A dual part, only lasting for a few seconds, turns the color scheme gray for the first and only time.

The gray color scheme continues as the music plays it's peaceful melody. A half-speed flying section consisting of spikes and gears make the player go slightly up and down in a wave-like one space fly. The background of the section flashes, revealing extra designs and thorns. The ship turns into a mini and continues the same flying style and color scheme. A small "Evasium" can be seen.

A mini wave comes after the ship, and spikes serve as obstacles only at the top and bottom. The correct path taken is shown when the background flashes. the only red things in sight are the gears near the ground. A regular wave follows, and the gameplay is much like michigun's wave part.

A regular 1x speed UFO follows, with rapid gravity change and purple orbs. The gray color scheme continues.

The UFO turns mini, and as the music accelerates and the drumbeat comes in, there is thorns and a line of purple orbs. A spamming up section is implemented as the song changes key and the level turns back to triple speed red and black.

Crack:

The song changes key, a full step up (D minor), but playing the melody before, only faster and more urgent. The background changes to a bloodred. The gamemode turns into a triple speed mini ship, and the gameplay is chaotic flying. Gears and ToE ring decor are found. After a brief 1x speed section, triple speed resumes and straight flying starts, making the player go through a clubstep-like "monster" with a half-space fly.

There is then a section where a yellow jump orb and increasing speeds are used, inside a 1-block tunnel.

There is then a section much like clubstep, with "monsters" at varying heights.

The next non-mini cube sequence starts at half-speed, but increases speed while giving the player a break; there is no need to tap. The color scheme and music is still the same. A "CRACK" is seen.

ASonicMen:

A triple speed mini UFO is next. The background turns a bit lighter and flashes to the beat. Gravity changes rapidly, and gears leave a one-space gap to manuever the UFO to the notes of the song. Clouds are scattered throughout the level, and pulsing circles can be found. The size changes midway, leaving a split second of double speed before returning to triple speed. After a few seconds, another moment of half-speed occurs before going back to triple speed.

Next up is a mini ball sequence at triple speed. The same style as before: thorns, clouds, and pulsing circles. More blocks than gears can be found, because this sequence is a ball. The platforms use gray and red, with black glow blocks. The platforms dim and glow brighter to the beat of the song. One part consists of nine blue orbs in a two-block space, requiring more spammng of the mouse or keyboard. After the spam, "ASONIC" can be seen.

After the ball part, the music undergoes a large change in mood and style. The key goes back to its original C minor as an auto cube part follows, with the objects' borders flashing chaotically and the background, too. This indicates that the song, and the mood of the level will be hectic and fast again. The end of the auto gives the player a split-second of half-speed before returning to triple speed.

Etzer:

A triple speed normal size UFO with a different style than the rest follows the auto. The music sounds similar to that from cataclysm in the first ship segment. It is slightly more artistic; more decorations and glow are used. Soon after, his name can be seen in block letters. The player must land on his name and tap a pink orb. After that, the player must undergo many gravity portal jump orbs; jumping while changing gravity.

Next is a 1x non-mini ship part. This part is slightly easier; there is actually 2 blocks to fly through. Players must fly under the gravity portal; it is a trick. The ship mode turns into triple speed for a second.

The next segment is a triple speed UFO. Two jump orbs are tapped before tapping a third one right inside a ship portal.

The next ship is a straight fly near the bottom, the place all black except for the tunnel the player's ship is in.

Havok:

A 1x speed original ball follows with the same style and blocks as vermillion's ball part, with jump orbs though. A mini portal and a half speed arrow make the gameplay harder after one second of full-size.

The gameplay turns triple speed after a second, and 4 jump orbs must be tapped, and the signature "HAVOK" can be seen.

Another UFO segment follows, changing speed and gravity. Saws instead of gears are found, held onto the blocks being obstacles for the UFO. Arrows are found guiding the player onto the right path, and the background pulses to the music.

GironDavid: 

Next is a half-speed regular wave. Here the player must manuever through a one-block straight wave, changing heights and gears here and there, similar to acropolis's final wave. The background pulses a brighter red to the beat of the music. A "G" can be seen just in front of the ship portal when the background flashes.

Next is a triple speed upside down ship. Jump orbs have to be tapped, and the fly is chaotic with only 1.5 blocks of space. At the final notes of the segment, a 1.5 block straight fly with a regular size ship ends the segment.

The next segment is a half speed dual. One cube is large, and one is mini. Consecutive jump orbs are tapped, and the word "GIRON" can be seen brighter than all the other blocks, with chains connecting it to the blocks and floor. A small non-dual auto, around .4 seconds, ends the section.

GgB0y:

A half-speed ball is next, similar to the one in Cataclysm. red blocks with chains in them are seen, and the words "your blood" can be seen. A one-second UFO is next, leading to the final ship, ball and cube. The final ship part is the same style as the ball, and there is a upside-down one block straight fly. The final ball many fake blocks and spikes laid everywhere as a last ditch effort to cause the player to fail. The name "GBOY" can be seen.

Riot:

The final notes holds a one-speed cube auto, with "GG" on the top of the cube and "RIOT" on the bottom. There is one last set of "invisible" triple spikes that the player must jump over, which will otherwise result in a very enraging and disappointing fail at 99% or 98%. After that, the level ends.

Fails

 * Mabby01 crashed at 61%, 66%, and 71%.
 * RpgRaketti crashed at 87% and 89%.
 * Sandstorm crashed at 74%.
 * Quantum crashed at 72%.
 * Quasar crashed at 90%.
 * SoulsTRK crashed at 79%, 88%, 92%, and 95%.
 * Riot crashed at 79%, 90%, 91% and 94%.
 * Surv crashed at 96% three times.

Trivia

 * This level took Riot over 30,000 attempts to verify. Even RobTop himself and Michigun had to encourage Riot to keep on trying.
 * Riot's most severe crash in Bloodbath whilst verifying the level, was at 94%.
 * Currently, this and Red World Rebirth Riot's only featured and rated levels to date.
 * There's an error in the level. It's at Etzer's flying section, where you can see an unfilled portion.
 * It was said that this level is the hardest possible level on this game, but then Mefewe got 98% on Sonic Wave, proving that Sonic Wave is possible.
 * To date, Riot, Surv, Quasar, and Souls TRK are the only players to have beaten Bloodbath legit.
 * Geometry Dash BULI claimed to have beat the level, however he later confessed to hacking. He is now trying to rebeat it legitimately, currently with 78%.
 * There is an easter egg at the very end of Bloodbath, at Gboy's part, you can position yourself to land on top of the "GG". If you manage to do this, the word "Michigun" will appear. However, Riot did not do this while verifying the level.
 * The next closest player to completing the level is RpgRaketti, with 89%. After that, there is Buli with 78%, Sandstorm with 74%, Quantum and Gonchus with 72%, Mabby with 71% and GironDavid with 46%.