Aincrad

Aincrad is the final area in the game and headquarters of the Sword Artists. It's a floating castle, containing 100 floors of various environments. Because of that, it's also the largest area, spanning three chapters. Various bosses reside here, including rematches of past ones. Aincrad exists in two worlds: reality and virtual. In reality, floors are extremely dark and filled with ghosts of dead players. In the virtual dimension, the environments are much more lively. However, the Emerald Guardians lose their classes and cannot use magic.

All Floors
Even though Aincrad is 100 floors, the Emerald Guardians don't traverse through them all. The following are the floors the heroes go through...

Chapter 13 (?)

 * Boardwalks (you start on the far left side)
 * Floor 1 (Plains)
 * Floor 3 (Forest)
 * Floor 22 (Forest and Lakes)
 * Floor 27 (Plains and Vallies)
 * Floor 55 (Mountain)

Chapter 14 (?)

 * Floor 59 (Plains and Forest)
 * Floor 60 (Desert)
 * Floor 61 (Ocean)

Chapter 15 (?)

 * Floor 74 (Mountain and Plains)
 * Floor 75 (Plains and Lakes)
 * Floor 99 (Kingdom)
 * Floor 100 (Ruby Palace)

Virtual
The only weapons sold/found in the virtual world are swords.

Reality

 * Sonic (Floor 3)
 * King Dedede (Floor 22)
 * Ridley (Floor 55)
 * Bubsy (Floor 61)
 * Asuna (Floor 100)

Virtual

 * Illfang the Kobold Lord (Floor 1)
 * The Four-Armed Giant (Floor 27)
 * The Gleam Eyes (Floor 74)
 * Skull Reaper (Floor 75)
 * Kirito (Floor 99)