It's actually not that complicated. The transition is made by dithering, so if the lower half was the original value and the upper half added some orange into the original hue, it doubles the amount of colors in total. Which also means, if I add more stuff, I'll probably have to expand to 24 colors or more, or remove the gradient.

The floor is currently made of 6x7 tiles. I thought, the overlaying transition could be chosen individually, or, becomes warmer/ colder, depending on the people living there :D

Wow it looks like a gradient, but yeah it's 17 colors. If it's for building your own house is the gradient overlayed on the floor you choose? Seems like it would be hard to tile

Ty! It's 16 colors, actually - http://yanrishatum.ru/pj/?input=http%3A%2F%2Fpixeljoint.com%2Ffiles%2Ficons%2Ffull%2Fjproom1.png (not counting transparency, though)

Really love that gradient effect. Although this seems to have more than 16 colors.