Hello!
*Transparency should be implemented at the engine/code level.
**5 - if there are only two colors in the game(black and white or their analogues), 4-if there are three colors in the game, 3 - four colors, 2-five colors, 1-more than five colors. (The same color with different alpha channels is not considered separate colors.)
This doesn't answer the question asked. I assume the answer should be no. If full grayscale is counted as two colors, RGBK covers everything a computer can display, so it's not possible for anyone to get fewer than 3 points for color usage. "Five colors" doesn't make sense if mixing colors is acceptable, so the fact that there's a "five colors" option means mixing colors (such as mixing black and white to get gray) is not considered just two colors.
The alpha channel explanation confuses this a bit, as I could make a fully-lit, detailed, and colorful 3D game by setting up my materials in three layers (red, green, and blue). By using those three colors with alpha channels over black, I can display the full range of colors that a computer monitor can display using only four colors. This obviously breaks the spirit of the rules and I should get 1 point for this, the minimum, but as worded in the rule, I would get 3 points.
