While playing around with the F# September CTP over the last week, I made a short, <300 lines, implementation of the Mastermind board game using some Windows Presentation Foundation (WPF) controls. I've been impressed with the integration of F# with Visual Studio 2008 with project references and property pages now in place. It also seems pretty easy to wire up a usable UI using the WPF controls event without XAML. Anyway you can view the source on the F# wiki or download it below and have a play.
Mastermind.fs (13.69 kb)