A Solitaire game below is played with a number of counters arranged in a circular pattern. One of the faces of each counter is red, the other is green. A move consists in clicking on a green counter. When you do, the counter is removed. At the same time, its neighbors (if any but at most 2 of course) are flipped over. The goal is to remove all the counters. Beware though that the puzzle is not always solvable. There is a simple condition to check in advance whether it is.
The applet allows you to take a move back (Back button) and to return to the same starting arrangement (Repeat button.)