Do you know the Mastermind game? MindsEye is a game that´s based on it, and so needs large doses of deductive thinking to win. The objective is still the same: guess the correct order of the sequence of four colours chosen at random by the PC.
In the easy level there are 7 colours to choose, in the intermediate there are 11, and in the advanced 15. You have to try combinations and pay attention to the clues: right colour, right colour wrong position, wrong colour, etc. Victory comes with getting all four correct.