Stars! Nova is a clone of the classic 4X space strategy game Stars!. While nowhere near the functionality of Stars! quite a few features have been implemented so far. See the Nova web page for details.
An editor for the open source game c-evo (http://www.c-evo.org). A suite of several different editors (unit graphics, tile graphics, nation files) with some interoperability. It is written in C# 3.5 using Visual Studio 2010.