For his video series Coding Adventures Sebastian Lague created a Chess-AI in Unity. I gutted my own C# chess engine, then copied the chess playing code from Sebastians Unity project over, changed what needed changing to make it compile again. The result is a chess engine based on Sebastian Lagues code that supports enough of the UCI interface to be used in your favorite chess GUIs.
To play with this version, which implements the UCI protocol, you need a compatible chess GUI. For example...
Then you either compile an executable from source or download from the most recent release, register the executable (e.g. SebLagueChessEngine.exe) with the GUI and you're ready to go.