The Drill Mobile (ドリルモービル Dorirumōbiru?) is a boss in Sonic the Hedgehog 3. The player will face the Drill Mobile at the end of Marble Garden Zone Act 2, though he/she can also confront it at some point before then. Depending who is the playable character, the battle against Drill Mobile will be different. Normally, it takes eight hits to destroy the Drill Mobile.
The Drill Mobile is created and piloted by Dr. Eggman (piloted by EggRobo in Knuckles' gameplay), and is mainly composed of the Egg Mobile connected to a wide flying vehicle. The Drill Mobile has two motors set on both sides and features a drill attachment on the front bottom. Depending on where the doctor is flying the Drill Mobile, the drill attachment can aim straight ahead, down or up behind the mobile. During the battle between Knuckles and EggRobo, the Drill Mobile is also revealed to have a chain of small spiked balls connected between the cockpit and drill attachment.
Sonic and Tails' Version
The first time the Drill Mobile appears is near the beginning of Act 2, inside a small temple. There, as the surroundings begins to shake, the Drill Mobile, with Eggman piloting it, will pop out of the ground in the right side of the hall. If the player damages the Drill Mobile once or leaves it undisturbed for while, Eggman will begin drilling into ceiling with the Drill Mobile and the player can normally continue on normally through the Zone. However, the player can still take damage from the Drill Mobile should the playable character touch its drill or engine part.
The Drill Mobile and Eggman will later in the Act reappear in another hall in a similar fashion to the first one, this time on the left of the hall. There, the doctor will make the temple surroundings crumble with the Drill Mobile, and after the player hits the Drill Mobile once, Eggman will similarly start drilling into the ceilling and disappear again. However the player has to go through the following section of the Act before the crumbling ceiling slowly collapses and crushes the playable character.
At the end of Marble Garden Zone Act 2, the player faces Eggman in his Drill Mobile on a flat portion of the ground. Here, Eggman slowly descends from above Sonic/Tails and destroys the ground by smashing into it and making the ground below collapse. The battle takes place in the mid-air, where duo keeps following the Drill Mobile with Tails carrying Sonic through mid-air. The player can use D-pad to make Tails fly any direction indefinitely. After Eggman has been flying in mid-air with the Drill Mobile for a while, the doctor will fly off off-screen. Depending on the side of the screen that Eggman flies into as he moves into the background, Eggman will re-appear from the said side of the screen and moves in an almost straight line to the opposite side of the screen, with the drill attachment aimed in the direction the Drill Mobile is heading. As mentioned earlier, the player has to avoid the drill and active engine parts below the mobile in order to avoid taking damage.
When the player decides to attack, Sonic can jump regularly by pressing jump button to perform a Spin Jump into Eggman on the Drill Mobile. If the player misses and falls off-screen, it does not count as a bottomless pit and instead, Tails goes after Sonic and carries him up into the screen again. If the player has Tails as playable character, the battle is more challenging, since Tails cannot jump in mid-air. The only way to damage the Drill Mobile as Tails is to go below the Drill Mobile and damage it with Tails' spinning tails while he is flying. After landing eight hits, the Drill Mobile gets destroyed and Eggman escapes. After opening a capsule in the mid-air, the player clears the Marble Garden Zone.
In the locked-on version of Sonic the Hedgehog 3 & Knuckles, Knuckles confronts the Drill Mobile earlier in Marble Garden Zone Act 2, where it this time is piloted by EggRobo. However, during the Act, Knuckles is unable to reach the last Relief on the wall. As such, the player has to climb up and go down a different pathway which is meant only for Knuckles.
After getting inside the temple, the player meets EggRobo in the Drill Mobile again who then flies up through the ceiling, causing the place to crumble. Like Sonic/Tails playthrough, the player then has to eventually go through the section with collapsing ceiling. After this, the player enters the another temple, where the player fights EggRobo in the Drill Mobile.
The EggRobo version of the Drill Mobile battle is different from the battle with the Drill Mobile featured in Sonic/Tails' playthrough. In this battle, the Drill Mobile will fire a chain of spiked balls from one of four different locations (either from the ceiling or from the floor) which will then re-emerge from another location. The Drill Mobile itself will then travel along this chain before repeating the process. The formation of the chaim is different each time, with the player having to look out for where the chain will pop out. The times where the Drill Mobile can be damage are when it comes out of the ceiling or the ground, though the player can take damage if touching the engine parts of the Drill Mobile. After hitting it eight times, the Drill Mobile gets destroyed and EggRobo escapes. After opening the capsule, the player clears Marble Garden Zone Act 2.
- In the Sonic/Tails version of the fight, if the player moves below the collapsing pillar, when Eggman destroys the terrain, the player will eventually get crushed by the pillar's upper part despite the pillar itself being unable to do so.
- It is possible for Sonic (and Tails) to fight Knuckles' boss using Debug Mode and vice-versa. When Knuckles enters the Sonic/Tails version of the battle, EggRobo is seen piloting the Drill Mobile, while Tails flies and carries Knuckles in the mid-air normally.
- Knuckles' version of Drill Mobile fight has mid-boss BGM playing at background for unknown reason.
- The Drill Mobile makes a small cameo appearance in Sonic Chronicles: The Dark Brotherhood, where it can be discovered as wrecked near close of EggRobo, capsules and Sega Genesis at the Metropolis.