Mastermind

The goal of this logical game is well known (english equivalent is Mastermind). You have to guess five hidden colors. Your attempts are evaluated by color marks - black means you have guessed both position and color, white means that the color is placed somewhere else. You need to reach five black marks, of course.
This program is very simple (it took about 4 hours to write it), but at least it will run at any PC.