Sentries

Sentries are unkillable, immovable objects that sometimes spawn exclusively in Mechtropolis.

They can appear in two colors, which determine the rotation. They usually spawn in the middle of the room, but can be found on top of cars as well.

Sentries attack by spinning 360 degrees, while shooting bullets at the rate of a Rapid-Fire Droid. However, their bullets do more damage, doing a whopping 10 per bullet. These bullets can be dodged by jumping, getting behind shelter, or jumping onto the sentry itself. After completing the stage, the sentry will shut off, and will never be active again.