Editions are special versions of the Chicken Invaders games that are usually based around various holidays. They come with the game if you buy one on InterAction Studios' website, or as DLC on Steam. The only game that doesn't have any edition made for it is the first game.
Editions usually replace graphics and music of the game with something related to the thing it's covering.
So far, there are four different editions:
These editions usually have the most effort went into them, with most of the graphics and music being replaced,for example, in Chicken Invaders: Cluck of the Dark Side's Christmas edition, only the Henterprise theme stood intact.
Christmas Editions are being made since Chicken Invaders: The Next Wave.
These editions don't have as much effort put into them as the christmas editions, but they are still good. Usually, only the graphics are replaced.
Easter Editions are being made since Chicken Invaders: Revenge of the Yolk.
In these editions, only the graphics and the main theme music is replaced.
Thanksgiving Editions are being made since Chicken Invaders: Ultimate Omelette, and so far it's the only game that has a thanksgiving edition.
Those editions are like the thanksgiving editions, since only graphics and the main theme are replaced.
Halloween Editions are being made since Chicken Invaders: Cluck of the Dark Side, and so far it's the only game that has a halloween edition.