Here’s a practice puzzle that I made for the color-themed team round at the WPC. Some of the intended logic may have been lost in getting it correct, but enjoy nonetheless.
Rules Place some red, green and blue light bulbs. These shine in vertical and horizontal direction until they hit a black cell. Every white cell must be illuminated, and no two bulbs may illuminate each other. Colored clues indicate the composite color of the bulbs that illuminate it: pure red, green or blue, cyan (green+blue), magenta (red+blue) or yellow (red+green).
Or see the WPC instructions.