Aincrad Realm

Aincrad is the world set as the stage for «Sword Art Online», declared to be the world's first VRMMORPG in history. It was incorporated in «ALfheim Online» on May 2025.

Setting
According to the dark elven legends, in the long-distant past, the world was split into the forest elven kingdom Kales'Oh, the dark elven kingdom Lyusula, the human Alliance of the Nine kingdoms, the underground realm of the dwarves, and various other groupings. While there were skirmishes at times, the land was at peace.

But one day, a hundred varied regions from around the world were cut into circles from the earth and summoned up to the sky. The circles were under three kilometres across at the smallest and over ten kilometres at the largest. They were stacked in a conical formation to form a gigantic floating fortress a hundred floors tall.

Geography
Aincrad is an iron-and-stone made floating castle that has about ten kilometers floor base diameter and consists of a hundred floors stacking straight upwards, meaning that each floor's diameter is a bit smaller than the previous one. On each floor, there are a couple of large cities along with countless small scale towns and villages, forests, plains, and even lakes. Only one stairway links each floor to another, and the stairways exist beyond the boss room of each Labyrinth. The «Teleport Gates»[4] of every unlocked cities are connected to one another.

It is possible to climb the outer circumference of Aincrad, but trying to climb beyond a floor that has not been unlocked will result in being blocked by a barrier and a visual error

The castle held its countless towns and villages, mountains, forests and lakes, and never again returned to earth. The magic powers that caused the old civilization to flourish were lost, and with them, the nine kingdoms of man. Most towns reverted to maintaining themselves, and the floors lost contact with one another. A great length of time passed. Legends and tales of the Great Separation (大地切断, Dai Chi Setsudan?) still existed among the two elf races, the only people to keep their kingdoms intact from that fateful time.

Monsters
A variety of unique monsters that can be found on every floor and in every dungeon in Aincrad. They are the main source of income for most players, as they drop Cor and other items to the victorious players. Like NPCs, monsters, except for most if not all Bosses, re-spawn after a certain amount of time has passed since they were killed

New Aincrad (ALO Version)

For Those Wishing to Role Play in the New Version
At the end of Fairy Dance Arc, with the sprouting of the «World Seed», some of the old ALO players funded a new company, Ymir, which bought all of the ALfheim Online data from RECT Progress Inc. for a small fee and discovered that a complete copy of the castle existed on the server. As the company had to fight a decrease in the playerbase due to RECT Progress' inhuman experiments and because the company was formed by veteran MMO game players who had been playing since the 2D age and could not bear the deletion of the intricately designed castle, the castle of New Aincrad was implemented into the ALO world, floating above the continent of Alfheim, on May 2025.

The castle is currently being cleared by guilds and players without a guild. Such raids are led by high-level players like General Eugene.

Changes in New Aincrad
The castle is essentially identical to the original Aincrad, except for a few key features. First, the bosses and dungeon monsters were made significantly more difficult, as there is no threat of real death in the ALO's Aincrad. Dungeon maps and similar features were likely re-done, as the Clearers in ALO continue to utilize mapping and scouting strategies on bosses, while all the bosses were changed to brand new ones. The last known change is on the Monument of Life. After this update, the monument, which before used to list existing players who were still alive at the time, is now called as the «Monument of Swordsmen» and is used to list players who participate in clearing the boss of each floor. As the monument can only record seven player names for each floor cleared at most (due to space limitations), if more than one party participates in the battle against the boss of the floor, only the name of the leader of each party will be listed on the monument, however, if one party of up to seven players is able to beat the boss on their own, the name of each member of the party will appear on the monument

Features and Restrictions in New Aincrad
Since Aincrad was fused with ALfheim Online's gameplay, the system was also designed to re-account for magic, flying, and the new limitations and additions with Sword Skills. It is now possible to fly from floor to floor in ALO's Aincrad, although the outer circumference is closed for floors which have not yet been unlocked. Additionally, a flight altitude limit for players is set at the level of the 50th Floor, preventing players from examining the outside of the floors above it, including the top of the castle. Dungeons are no-flying zones, and the Remain Light system was incorporated from ALO.