I was playing a game called Space Rangers earlier, and stumbled upon a "text-adventure" mission in it, which required me to find what's supposed to be the only possible solution to this puzzle.
I have a field of 3x3 tiles, numbered 1-9, such as
        
I can chose TWO numbers, except for the number 9, which is "not working" according to the in-game explanation.
Each number is either white or black, and when I choose a number I find out what color it is. It seems that 5 is always black for some reason.
After choosing two tiles, the game will perform a test and tell you if there are possible "solutions" (as in, possible vertical lines or possible squares of black tiles), while knowing the color of your two chosen numbers.
The possible "solutions" to the puzzle is a vertical line of black tiles, or a square of 2x2 of black tiles.
I must guarantee that there is only one possible solution, as in, only one possible line or square that are all black.
Which two numbers should I choose?
I have thought it over for a long while, and the only idea I could come up with would be 4 and 6, but one of them is ALWAYS black, making my attempt at getting both as whites to mess up both vertical lines and squares in each side...
After countless attempts and even more half-hearted attempts, I gave up, accepting that I failed the mission, and moved on.
But I'm curious, as I assume it is possible one way or another (I just fail to see something that's probably obvious). What would be a working solution to this puzzle?