Entry for Pixel Art Challenge: CHALLENGE 2000.
rule:
Canvas Size - Min 100x100.
Colors -
You need to use 3 or more colors.
A maximum of 3 colors can be placed per line.
2 sets of 3-color line palettes can be held, one for even rows and the other for odd rows.
As an exception, for animation frames or series artworks, changing line palette colors on a per-frame image basis is permitted, but each image must not exceed 6 colors in any case.
Transparency - Forbidden.
Animation - Optional. | 
Weekly Challenge: CHALLENGE 2000
Fascinating. Your colours are really nice. Coupled with the rules, they create an interesting misty effect. I particularly like the middle image, where the use of the greeny-yellow is especially effective.