Erebus is a 2.0/2.1 Extreme Demon collaboration created by Rustam and Ilrell that was started in 2.0 and verified during 2.1 by BoldStep. It is themed and designed around the idea of a "radioactive facility". The level is unique in the sense that it is one of the only top 50 demon levels with a primarily green color palette, with its closest contender being the Nine Circles level Down Bass, positioned at #50. It is currently placed at #6 on the Official Geometry Dash Demon List, above Yatagarasu (#7) and below Sonic Wave (#5).
0-13%: The level starts the player off with a triple speed mini ship sequence with some art in the form of a robot at the very beginning with the text "Ilrell & Rustam" "Erebus" and "Boldstep" easily visible directly underneath the art piece. The first bit of game-play then follows in the form of a half speed difficult mini ship sequence with some gravity switching from both portals and jump orbs alike. The level transitions to a tight mini wave segment with size switching instead of gravity this time. Coming up is a short ball featuring several blue jump orbs which require difficult timings in order to get through, and right after, a tough upside-down ship sequence containing the first of the two coins which can be collected via a tiny straight fly. More straight flying follows as the ship turns mini and transitions into the next part.
13-39%: This section adds an extra layer of mystery to the song and bumps up the speed as well. First, a four spike jump immediately followed by a hard but short straight fly and an insanely narrow mini wave segment and a fast mini robot right after that with lots of difficult orb timings. Soon the robot turns into a cube and proceeds into a line of pink orbs, a blue and green orb, and yet another line of pink orbs. Some more orb timings appear as the player now enters a mini straight fly, which if passed, will be awarded by the long auto coming up. This auto segment takes up about 8% of the level and consists of a large text saying "Erebus" in the background with a custom font.
40-61%: The player then enters a mini ship sequence and is thrown into a barrage of extreme gameplay starting with a single green orb straight into a ball with insane timing and a short, near-impossible mini straight fly followed by even more timing, this time as a cube requiring blue orbs in both the air and ground to be tapped as well as a green orb and another blue orb leading the player into a UFO with even more extreme timing with orbs. Following this is a cube maze located right before the drop which has very limited vision and tons of fake orbs. Not only that, but it also turns dual for the last few seconds as well, then the drop appears.
62-80%: Here it starts off as a mini straight fly leading into an extreme mini wave segment, then a cube section, all in the span of about one second. This cube is filled with orbs of both green and blue variety, and they all require insane timing as well. Next up, there is yet another tiny straight fly into a ball with some more insane timing as it now enters ship form which tests the player's maneuverability through a decently long part followed by a spam wave into another tiny straight fly quickly turning into a cube afterwards. Like earlier cubes, this one contains lots of orbs testing the players timing with both blue orbs and a pink orb. A short but insane mini wave comes next leading into the last 20% of the level.
81-100%: The wave turns into a symmetrical dual cube with a jump and a pink orb into a similar segment, although now played as a ball. Following this ball is what is considered by many the hardest part of the level, referred to as the dreaded ship, according to BoldStep himself. A ship sequence of such extreme precision, stretching over 2.5 seconds and located 85% into the level, is only one of the reasons why this level is as high up on the list as it is. If passed, the player will turn into a triple speed mini cube with some of the final insane orb and jump timings of the level right before the last straight fly and a single ball tap into a short auto leading the player to the final jump of the level: a five-spike jump. Located on a platform held up by two fists, this serves as the final click of the entire level and will grant the player with the second and final coin of the level and the text "Verified by BoldStep," "Layout by Ilrell," "Decorated by Rustam" and "GG." Then, the level ends.
User Coin 1: At 11% in the ship sequence, if the player goes through the narrow passage between the spikes, the player will obtain the first coin.
User Coin 2: The player obtains this coin when he completes this level after jumping over the spike at the end.
Despite its extreme difficulty which ousted almost all other demon levels upon its release, it is one of the shortest extreme demons, only standing at roughly one minute and ten seconds long.
The difficulty mostly derives from its inconsistency compared to other levels, the gameplay having numerous bugs that cause the player to crash.
A few parts in the level were remade for the final version, including the 8% long auto. This originally contained one of Rustam's high detailed skulls (now used in Yatagarasu) and the text "Still not dead?" written beside it. The second revision of the auto segment also contained the skull but instead of "Still not dead?" it was an actual logo for Erebus.
The cube maze right before the drop was also changed a bit. Although the game-play did not change, lots of black translucent bars were added all over the screen to obscure the player's vision and further increase the difficulty of the level.
The level started its life on the Official Extreme and Insane Demons Ranking List as #3, behind Yatagarasu and Sonic Wave, but its difficulty was soon realized and it was moved above Yatagarasu on the list and claimed the #2 spot. Then, on July 18th, it became subject to another underrating, and was moved above the legendary Sonic Wave because of the very few victors, like EndLevel, stating that Erebus was in fact harder. And so, with all of this in mind, it was put at number 1 on the list.
Skullo has a pink and blue version called Guccibus.
In Greek mythology, Erebus is the god of darkness and shadows, as well as the brother of Gaea, the goddess of nature and the earth.