ZERO/Pre-SGW

ZERO (serial number and codename E-100 "Alpha") was the very first prototype of Dr. Eggman's E-100 series robots. An early and experimental model, the Alpha model had design features that made them unique to most of it's successor "brothers." E-100 Alpha robots were used to track down and capture a green Flicky, as well as Amy Rose, due to her aged body containing powers left over from the Ring of Acorns (which was forged using a Super Emerald and thus could be used to evolve Chaos further).

Use to Capture Flicky
For unknown reasons, a group of E-100 Alphas were tasked with chasing and retrieving a green Flicky. The Flicky had managed to flee to the Hidden City of the Ancients, where it was then protected by Amy Rose. Amy managed to destroy one of the E-100's with her Piko Piko Hammer, but two more showed up and captured her and brought her back to the Egg Carrier. (StH: #81)
 * The E-100's were likely tasked with retrieving the Flicky to place it within one of the E-100 models, similar to those trapped within E-102 Gamma and the other E-100's. This is the case in the game Sonic Adventure, though was never specified in the comics.

Decommissioned
Eventually the E-100 units were decommissioned and scrapped by the Eggman Empire. As such, they were ignored by Gamma during his quest to liberate the rest of his "brothers." (ASUB)

Design
The E-100 Alpha's form completely lacked any legs employed by the four E-100 series models, instead using some kind of propulsion lift to allow it to move around, similar to the upgraded E-101 Beta model. It's basic shape seemed more like a large box, removing almost any semblance to a overlander template. In addition, Alpha had only a single shoulder-mounted laser cannon built into it which had poor aim; a stark contrast to E-123 Omega, who was primarily made up of weapons. Its primary "weapons" were a pair of arms with fist-like manipulators, making it suitable only for melee combat or dealing with weaker enemies.

Background Information

 * The E-100 Alpha's were likely tasked with retrieving the green Flicky to place it within another E-100 model, similar to those trapped within the other E-100's. This is the case in the game Sonic Adventure, though was never specified in the comics.
 * E-100 Alpha's coloring design differs significantly from its game counterpart.
 * In the Sonic Adventure game, E-100 Alpha was more commonly referred to as "ZERO."