E-103 Delta was a humanoid robot colored in blue and white. He possessed no neck, his head and torso coming together in an almost ellipsoid shape. His torso was blue with a wide and white vertical stribe down the middle, and possessed a head light with a hexagonal gray frame on the right side. He also had gray mufflers surrounding the pelvis area, and had the number "103" painted in white on the right of his large vertical stripe and the left side of his rear. His head meanwhile was small and platform-like with a yellow shade and green cylindrical eyes. He also had a Jet Booster hovering behind his neck.
Delta's shoulders were black vertical cylinders. Attached to each of them were Delta's arms, which were long and designed with two joints; each of Delta's forearms were designed as blue gun barrels. Originally though, his left arm held a black-gray blaster while his right arm had a tri-digited hand with two points of articulation on each digit. Also, Delta's upper arms were blue, while the parts between his upper arms and forearms were gray. Delta also possessed two long and inverted legs with five points of articulation and large, black feet with two sharp toes and roller wheels on the heels. The upper sections of his legs in particular were blue while the rest of them were gray, except from his calves, which were thick and blue.
Along with his brother E-Series robots (E-102 Gamma, E-104 Epsilon, and E-105 Zeta), Delta was sent by Doctor Eggman to retrieve Froggy, who had swallowed a Chaos Emerald. When Delta failed to locate the correct frog, Eggman banished him from the Egg Carrier along with Epsilon. He stares at Gamma as he is teleported away, but it is unknown whether any feelings were stirred in the robots.
It is later revealed that he was abandoned at the Windy Valley. Gamma later tracked Delta down, intending to "rescue" Delta by destroying him, thus releasing the animal trapped inside him. The two brothers battled, and Gamma emerged victorious. Delta was destroyed, and the Parrot inside him was freed.
Powers and abilities
At first, Delta is a clone of E-101 Beta, with just a target locator scope, an arm cannon and a hand. After being discarded by Eggman with his scope removed, he received twin missile launchers in place of his arm cannon and hand and a Jet Booster.
Delta is a relatively simple boss, using the same attack patterns as E-101 Beta. However, it should be noted that Delta is quicker on the draw than Beta.
In gameplay, Delta will stay in one place and shoot homing missiles at the player, or take to the air with his Jet Booster. Use the open space to keep the distance and stay out of trouble. If the player does not let Delta get on top of them, they will have enough time to target and destroy his homing missiles. After the player take out any threatening missiles, lock on to Delta and fire. After landing five blows on Delta, this boss will be defeated.
Despite his lock-on ability in his upgraded form, Delta visibly lacks a targetting sight like Gamma.
His Jet Booster seems to let him fly for a short amount of time, instead of hovering like Gamma's.
Although he no longer has a functional forearm due to his missile upgrade, a mirror reflection of Delta's original forearm still appears on his front skirt plate. This is due to the fact the reflection is an actual painted image within Delta's textures, which was repurposed from Gamma's textures.
There is a glitch where right before the boss fight; if the player was to jump of some high elevation and fly to the left, Gamma will land on a rock sticking out of the mountain, allowing him to "snipe" Delta.