Connect Four (.NET version)
I had already written the Connect Four AI (see the applet version), so this was basically a test to check out Microsoft's claim of .NET's various languages being able to talk to each other. I had learned VB.NET first, so I did the UI in that language. After I got the basics of C# down, I decided to try and port my AI into a C# dll to call from the VB front-end. It worked beautifully. Since most of the Java logic was homegrown (not too much framework), it was pretty close to a straight copy from Java to C#. The syntax is so similar, I just had to tweak the declaration of a couple variables and viola! You can download and play with the .NET Connect Four here.