Your objective is to crack the code. Each time you try a pattern, you'll be given green and yellow circles.
For each yellow circle it means that one of the dots in the pattern you tried is present on the code.
For each green circle it means that you got one dot at the right position.
If you get a red X it means NONE of the dots in your pattern are present on the code.
Anyway, it's fun, it's free, and it's ad-free. Enjoy!