Asteron is an automated defence drone created by Dr. Eggman. These star-shaped Badniks act as anti-personnel mines which will remain planted on walls and ceilings within Eggman's bases. When an intruder draws near, the Asterons detach from their resting spots and float towards the enemy. After a few seconds, they explode and scatter the steel spikes on the end of their limbs in five directions, skewering anyone unfortunate to be caught in their path.
Sonic the Hedgehog 2
Asterons are encountered in the Metropolis Zone, anchored to walls and immobile. When the player is nearby, the Asteron will detach from the wall and slowly float towards the player. After two seconds, it will explode and launch the five metal spikes at the end of its limbs. The player cannot destroy Asterons by attacking them and can only avoid them.
Sonic the Hedgehog Pocket Adventure
Asteron Badniks make their next appearance in Sonic the Hedgehog Pocket Adventure, where they are featured in the Gigantic Angel Zone. As Gigantic Angel has many identical gimmicks and elements from Metropolis Zone, it has also the same Badnik models with similar attack patterns. However Asterons are seen hovering in the air and the player is able to destroy these Badniks before they self-destruct, thus freeing the animal inside of it. Asteron Badniks also are seen flashing red before exploding.
Sonic the Hedgehog 4: Episode I
Asterons make a reappearance in Sonic the Hedgehog 4: Episode I, with a slightly different design. They are featured in the Mad Gear Zone, which againis based on Metropolis Zone and has the same Badniks. Despite that, these Badniks retain identical patterns from previous appearances, but the player is once again not able to destroy them. In this game, before their self-destruction, these Badniks spin around.
Asterons appear in Sonic Mania's Press Garden Zone, though not as regular enemies. During the stage, the player will encounter stone reliefs built into walls that launch Asterons which can be seen on their sides. These Asterons will hurt the player if touched while in motion. After being launched, these Asterons will become embedded in the wall opposite the relief they were launched from. While stuck in the wall, the player can use the Asterons as a temporary foothold. The Asteron will fall a few seconds after being jumped on.
As well as being obstacles in the stage, Asterons are also featured during the Act 2 boss fight. The Heavy Shinobi, one of the Hard-Boiled Heavies, will throw Asterons like shurikens at the player. Unlike the ones encountered during the stage, these Asterons will explode in their usual fashion and scatter their spikes upon detonation.
In the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics, several Asterons guarded the Metropolis Zone during Operation: Clean Sweep which Sonic faced on his way to the core of Eggman's base.
After the Super Genesis Wave rebooted the timeline, Asterons became virtually identical to their game counterparts. Here, they are stationed in the Metropolis Zone as the Badniks used by the Metropolis Egg Army.