Ice Carbon Diablo X

Not to be confused with Ice Carbon Zust.

Ice Carbon Diablo X (commonly abbreviated to ICDX) is a 1.6 Extreme Demon created and uploaded by Roadbose, known for its excessive straight fly usage. Riot was the very first player (including the verifier) to complete it legitimately. This used to be one of the hardest levels in Geometry Dash, the other being Cataclysm (the old unbuffed version,) until it was discovered that Roadbose hacked the level's verification. Which of these levels is harder, and ultimately the hardest demon, has been a matter of debate among Geometry Dash players for a long time. However, with the creation and legitimate verification of Bloodbath many arguments upon this subject were disbanded, as the community now knew which demon was the hardest. Nowadays it is considered as one of the easiest extreme demons. It now sits at #98 on the Official Geometry Dash Demon List.

Gameplay
The level starts off with a moderately difficult cube section, consisting of an difficult jump over a sawblade. Next, the player enters a very hard ship sequence, going through very tight spaces and tight diagonals. It then goes into a very short ball, which has a blue orb over a spike. Then, the player enters a UFO part, which has a very hard first obstacle requiring near-perfect timing, then it goes into anti-gravity, then a size-portal. It then goes through a one-block space through a cube portal, while still in mini mode. The cube is relatively simple involving a few fakes and simple jumps. In a part in the cube section, there is a trick ship portal meant to kill the player. After passing the UFO portal, the cube segment becomes significantly harder with more skill required. It then goes into a very brief UFO segment where the player has to avoid a ship portal, then go through the "Demon-heads" into another cube section. After that, the ship part that follows is extremely hard, consisting of one-block spaces and invisible spikes. A slightly hard mini-cube then follows, which passes through a simple UFO segment, then returns to a cube segment, which then becomes an anti-gravity ship sequence with a tight diagonal space, which then reverts into a cube segment with a few obstacles. A very hard ball part comes after, involving timed switches, fakes, and orbs. It then enters an easy mini UFO segment which is nearly identical to Clubstep's first UFO segment, then passes through an easy ship sequence into a hard cube segment, involving a lot of timing and numerous fakes. It then transitions to a very hard ball segment, which requires even more timing and memorization skills compared to the one before it. After that is a very hard ship, which is almost entirely made of one block spaces, then into a cube with numerous fakes. A ship sequence similar to the second one follows, which then becomes mini and goes into a semi-tight diagonal part, then goes back to being a cube, and then a very short one-switch ball comes and instantly reverts to cube, which then enters the last part of the level. At 95%, a mini-ship sequence that has one block spaces with routine gravity portals starts, then the player arrives at the creator's name and the last one block space. Then, the level ends.

Trivia

 * This level was once thought to be humanly-impossible until Update 1.9, when Riot completed it.
 * Andromeda originally hacked the level, but later had re-beaten it legitimately as the start of his redemption.
 * This level had originally had more dislikes than likes due to being hacked. However, when Cyclic completed it, it received a huge number of likes, turning the ratio around to positive.
 * On March 1, 2017, this level was accidentally hacked by cos8o, when it and all of Roadbose's levels but not GW RoadMC2's were all somehow moved to Powerbomb's account.
 * This is close to falling off the top 100 demons list. This is very ironic, because the community used to consider it an impossible level on par with the likes of Silent Club.

Fails

 * Riot crashed at 95% due to bad timing.
 * SrGuillester crashed at 95%.
 * Satcho crashed at 95%.
 * Sandstorm crashed at 96% due to bad timing.
 * GoodSmile crashed at 96% due to bad timing.
 * Mabby01 crashed at 95% and 96%.
 * MaxiS9 crashed at 95% twice.
 * Andromeda crashed at 83%, 95% and 96%.
 * TrusTa crashed at 95% and 96%.
 * R3YGA crashed at 96% and 98%.
 * GuitarHeroStyles crashed at 87%.
 * AzaFTW crashed at 87% due to flying too high in the ship sequence leading to a timing error in the cube section.
 * Ozzy612 crashed at 97% due to bad consistency on the straight fly section.
 * EricVanWilderman crashed at 95% due to descending too far just before the straight flying near the end of the level. He beat it a few days after.
 * lFuZioN crashed at 96%.