To date, I have written three interfaces to the C algorithm. The first is a simple text-oriented interface that can be compiled and run on just about any machine. The second is a pretty nifty SGI interface that I wrote for a Computer Graphics course at The University of Waterloo. The third is an HTML interface (based on one initially written by Daniel Gordon) that allows a user to play the game over the World Wide Web. I've also written versions of the game for the Commodore 64 and VIC-20. All of this, and more, is available from this page. (Wow!!!)
Since the algorithm is so flexible, it's really easy to write several different front-end interfaces (with different looks and feels) for it on a variety of platforms. I encourage you to try writing your own interface.
Connect Four® is a trademark of Hasbro. I designed and implemented an algorithm to play the game, not the game concept itself.