BG-track is a background in Powder Game and Powder Game 2 that makes any element and object visibly "stay" on the screen, even after this element or object has moved or been removed. Other tools and objects held by BG-track include block, grid, players, wheels. Elements and objects will be held even if reset is used. The traces left by elements and objects on BG-track are affected by changes in air pressure, causing these traces to fade out. BG-track was added to Powder Game in ver6.3 and to Powder Game 2 in ver4.5.
A bubble rainbow occurs when the player creates a bubble in BG-track. After few seconds, a huge, colorful circle appears.
Laser charged glass
Laser traveling inside glass doesn't leave trace. This is because glass changes back and rewrites the track filter, and the same effect can be found in thunder charged metal. This can be used to create a hidden message or picture.
Example: 赤と黒(BG-track) by としあき (from Japanese section)
Fill with color
BG track can be used as "fill with color" tool in simple pictures.