Pit, 000,000,000 (RGB, black color)
Wall, 000,128,000 (RGB, green color)
Walking area, 000,064,128 (RGB, blue color)
...but there are other colors out there. I only know about Yellow, but there's gotta be colors for water, ice, snow, and pits you can climb out of (please, someone tell me if you know it, so I can make the BKIII mod!).
The Hidden Color
Stage 7 Elevator Barrier, 248,252,000 (RGB, yellow color)
If more colors are discovered, they will be listed here.
How to use Yellow
Yellow is quite infamous for its apparent glitchiness, but I think we're all just using it wrong. I hope to have the definitive guide on how to use this damn color some day, but I believe I've hit pretty close with it.
Yellow can make ledges. You can jump up through green and stand in a yellow area.
Do NOT make the ledge more than 1 pixel thick (unless you know what you're doing - see Benny26's replies). Remember this, and your ledges will be fine and glitch free.
To drop from a ledge, press up/down. Or run to the left or right of it.
Make sure that there is a blue pixel somewhere for you to land when you drop. You don't want to drop in to green territory and get stuck.
To make a ledge that runs up the screen, draw stripes as wide as possible up the rail.
Leave one pixel between each stripe and the one above it.
In any column of pixels, there should be no more than 2 yellow pixels. Following the previous rule, there will be a blue pixel between these 2.
If you have 3 or more, you're going to get loaded with glitches - shorten stripes until you can avoid this. With 2 pixels, you have good collision for jumping on the rail combined with minimal glitching when walking under the rail.
To escape a 'glitch' when walking under a rail, move diagonally.
Not properly tested: Since you drop off of ledges when you run in to green, I concluded that sticking a green pixel on the side of a ledge may help reduce glitching. Testing seems to have supported this, but I may have just been biased.
When you don't stick to 1-pixel-thick stripes and paint blocks of yellow, it can be used to make special walls to throw people over!
The wall must be at least 3 pixels thick vertically and horizontally.
Try to make it as thin as possible without going under that limit.
Generally, you need to be close to the wall to get a successful throw or anti-air knock-down, but it provides marginally better results than using the 'thin green wall method' (see spoiler).
Important: When making a yellow wall, test the ends - top and bottom.
If you can slip through them to your death, add green around them to correct this.
Combining this Knowledge: SoR1 Stage 7!
CajNatalie wrote:Further investigation has shown that you shouldn't use a green wall, but a yellow wall.
That's right, yellow acts as a wall if you block it together.
If you want yellow as a ledge, it should only be one pixel thick! Because otherwise it will trigger the wall behavior that everyone labels as a glitch.
Yellow walls seem far easier to throw over. I even got knocked over it when I was hit during a jump.
Jumps don't have throw locking (each frame of a throw animation locks the victim's sprite in to a certain position, which is how you can throw/slam people past a thin green line - they'll get 'locked in' on the other side of the line), which helps support the reason to choose yellow over green for a better barrier effect.
Here is the magic map...
Now I'm going to actually... make Stage 7 (finally, lol).
If anyone can improve the ledge, please share how.