Unidasu

Orbinauts (Unidus, ウニダス in Japan) are badniks created by Doctor Robotnik. It makes its first appearance in original 16-bit version of Sonic the Hedgehog. It is a blue variety from the sub-series with same name that becomes red when an enemy is spotted and sends the four spiked balls around it forward to attack.

In North America the badnik has been called Orbinaut which is the same name for similar badnik at Star Light Zone, though they are known as Unidus in Japan. There are also E-series robots based on Orbinaut called E-15 Spiky Spinner in Sonic Adventure and E-32 Unidus in Sonic Adventure 2.

Sonic the Hedgehog (1991)
First appearing in 16-bit version of Sonic the Hedgehog, Orbinauts travel almost all the time at underwater sections of Labyrinth Zone. These badniks usually are conformed at cramped passages, thus being at the player's way. The player has duck to avoid its released spike balls and then defeat it with Spin Jump as Orbinaut is totally defenseless. Orbinauts later also appear in the third act of Scrap Brain Zone.

In 8-bit version of the game with same name, these Orbinauts have unusual appearance, with light blue orb and spike balls. Like in 16-bit counterpart, Orbinauts appear at Labyrinth Zone having the same pattern.

Sonic Adventure
New models of Orbinauts are made by Doctor Eggman in Sonic Adventure, being part of E-series and getting renamed as E-15 Spiky Spinner, which appear generally at Speed Highway and Sky Deck with having now two attack patterns.

Sonic Adventure 2
Another new model of these Orbinauts appear in Sonic Adventure 2 being renamed as E-32 Unidus. In the game Unidus can be found at Hidden Base and Death Chamber. Unlike Spiky Spinner, Unidus don't throw its spikes away but keeps bustling around.

Sonic Rivals 2
E-15 Spiky Spinner appears in Sonic Rivals 2, only being featured as collectible card. The card is able to collect by getting the high score in boss duel of Neon Palace Zone.

Sonic the Hedgehog 4
Orbinauts make reappearance in Sonic the Hedgehog 4 along with other ones from Star Light Zone as both of them having upgraded design. Both types are called Orbinauts in the game and are featured in Lost Labyrinth Zone. Despite the appearance, both types appear to have same patterns from their first appearance. However Unidus varitions already have full red appearance during the encounter with the player.

Sonic 4 Website Info

 * The Orbinauts return as one of Sonic's most challenging Badniks! Pay close attention, you only have a split second to defeat them.

Sonic Lost World
Both Unidus and Uni-Uni types of Orbinauts make appearance in both versions of Sonic Lost World. During the game, it turns out that badniks, including Orbinauts, got hijacked by the Deadly Six. Like in original Sonic the Hedgehog, Unidus types of Orbinauts are seen hovering around with spinning spike balls, while having blue colored body. Unlike Uni-Uni types, when the player comes close on the Unidus, it will turn into red and throw all spike balls to the lateral direction.

In Wii U version of the game, Unidus types can be found at Frozen Factory Zone 4 and Sky Road Zone 4, where they are only featured in 2.5D sections. In Nintendo 3DS version of the game, they are featured at casino-themed Sky Road Zone 2, where they are seen in 3D sections instead. Unlike in Wii U version, Unidus types will never fire their spike balls or turn into red.

Physical Appearance
As being part of the sub-series created by Doctor Robotnik, Orbinaut has similar appearance comparing to its other variant in Star Light Zone and other variants in general. The only difference is its coloring, as being first dark blue with red spike balls and getting angry at underwater it changes its color scheme to complete red.

E-series robots in Sonic Adventure and Sonic Adventure 2 have complete black color scheme with more metallic look. Robots also got small motors behind of them which makes possible to hover forward.

Abilities
What makes this Orbinaut variant different is its way to shoot spike balls to its target. As seeing at its eyes, it releases its spike balls in order from bottom of its core. Spike balls move at slow speed, however avoiding them underwater makes things hard due the heavy movement. In Sonic Adventure and Sonic Adventure 2 the attack pattern of E-series robots is more and less variable.

Archie Comics
A small team of Orbinauts have appeared in issue 227 of Archie's Sonic the Hedgehog comics, which suddenly attacks to Sonic and the group in deep underwater of Labyrinth Zone. As Sonic discovers a hole in underwater wall and breaks it, he manages to create the column and thus the underwater vortex, which sucked in Sonic, Sally, Rotor, Antoine and Orbinauts in. As all of them now are sliding down the waterfall, Sonic and Sally manages to jump to the other side as receiving the hand grip of Rotor. Unfortunately, Antoine and Orbinauts fall down to the pit, however being seen to survive at Scrap Brain Zone in later.

The appearance is similar to specific one from Robotnik's badnik army at early issues, having dark blue orb and grey spike balls. Instead of the balls themselves, these Orbinauts actually shoot spikes from spike balls. Oddly, the Orbinauts also got mouths.

Trivia

 * The Unidus variation is known as Unidasu in Sonic Jam. This is a transliteration that it is considered outdated as of Sonic Rivals.
 * There's been difficulties, especially in comics to recognize which type of Orbinauts can be appearing during the time. There's also been problem to recognize if the Orbinaut is a Unidus or Uni Uni one due both having same physical appearance but different color scheme in games. Major example is in Archie Comics, as Robotnik has created only single Orbinaut that has dark blue appearance, similar to Unidus one. However in several times, it happens that Orbinaut has same color scheme as Uni Uni one.
 * This is the same problem that appears in issue 11 at Sonic X comics as Orbinauts have dark blue appearance with orange spike balls and appear at Star Light Zone. Although it is obvious that these are the other variants of Orbinauts due the zone where it appears in the game.