Vexed
Vexed, the classic Palm game made in C# for .NET 4
This is a full remake of the original Vexed for the Palm in the style of the Psion version by Ewan Spence which I loved.
All the original level packs are there as well as the features from the Psion version (save/restore state, blocks remaining, undo and solve).
It's one of the best puzzle games I've ever played and decided it needed a makeover for Windows.
Open source, of course, you'll find the original on Sourceforge still at http://vexed.sourceforge.net/.
I hope you enjoy...