BG-g-map is a background effect in Powder Game 2 implemented in ver1.3. This background is used to show gravitational fields of the game screen with blue color, simulating a pulling field, and a green color, simulating a repelling field.
Originally, having gravity on would affect BG-g-map in a way that filled the screen in blue. This was later changed, probably to make other gravitational fields easier to see.
Showing the strength of gravity fields in uploads that have Black and White holes as a special characteristic, such as Playercourses or anti-gravity chambers.
Glitches[]
One very odd glitch is often overlooked because it doesn't happen right when the upload is viewed.
Having gravity off, arrange two Black holes and two White holes in a square, where the similar hole is diagonally opposite from it (works best if on one corner of the screen).
Turn BG-g-map off, then back on again.
The effect creates curved gravity lines far from the holes, similar to the curved magnetic field of the Earth. Reloading fixes this.
Continuing with the pattern, in which it appears that one of the holes is in the form of a 4x4 circle (the other hole filling in the rest of the 4x4 square), it creates a fuzzy blob of very small blue and green fields far from the square (example ). Clicking gravity off, then back on, creates a combined effect.