The Sky Stage, or simply Sky (also known as the Sky Platform or Air Box), is a secret stage found in Killer Instinct (1994) and Killer Instinct 2/Gold. It can be accessed in both games by holding Down+MK on both controllers after the players' characters have been selected.
The stage is best described as a platform levitating high in the sky, where the fighters engage amongst the clouds.
(NOTE: When fighting on this stage, it is advised to use extreme caution while playing, because the slightest move (i.e. uppercuts) or the slightest jump can cause a fighter to fall off the stage at any time, resulting in an instant KO.)
Knockoff (Stage Ultra)
In Killer Instinct (1994), the fighters can knock each other off of the sky platform towards their demise, landing face-first in some sort of desert, leaving behind a cartoony person-shaped hole in the ground.
In Killer Instinct 2, the stage finisher sequence is still intact, but this time, when the loser falls, it shows them falling towards their death in some sort of highway intersection above a town or city.
The KI Gold version is simply the loser falling to their death and mortally hitting the ground offscreen.
- In KI2/Gold, the theme of this secret stage is not on the official Killer Instinct Gold Cuts soundtrack, nor is it officially named (other than "Sky").