Powerups

Powerups are pickups that are dropped by Enemies and some boss phases. They appear as glowing yellow, blue or red orbs (for Accelerate, Shutdown and Firepower respectively).

If left on the ground, powerups will cycle through the colors slowly, from yellow to blue to red, then back to yellow, and so on. The color changes every 5 seconds.

A powerup's starting color depends on the time that it spawns at. You can imagine a powerup as cycling through its colors in the background before it's spawned. The order of the color changes is the same, but five times as fast (one change per second). This allows you to control powerup color if you can play very consistently.

Powerups drop after a set number of enemies are defeated, after which the next enemy not over a pit or an island will drop a powerup when it is destroyed. No more than 3 powerups can exist at once, although progress towards the next powerup can still be made.

Unlike Batteries, powerups will not block transitions within a stage and are immediately destroyed if the stage places a wall or pit at their location, or isolates the powerup from the player (such as being left on an island made just for turrets).

Spawning algorithm
Powerups spawn every set number of kills, the score value of each kill doesn't appear to be important. The kill quota and occurrence of the first powerup varies between levels. There is also a minimum time allowed between powerup spawns.

Powerups will never spawn on isolated areas or over pits.