Play Reversi against another player on the same computer. Click on the board to place a piece.
This is based on a Java program that I wrote about ten years ago. The Java version has some features that this version doesn't yet have, like being able to play against the computer, and changing the color of the board. You can play (a slightly updated version of) that Java program as an applet, Java Web Start application, or a regular application; or you can download the source.