A "baby's first" multi-threaded chess engine in Java I developed in October 2010. It plays a weak game of both classic chess and gothic chess. Some of the more complicated rules are probably wrong/missing (draws, castling), and it doesn't support underpromotion.
Obtain a JDK, then compile and run:
$ javac com/nullprogram/chess/Chess.java
$ java com.nullprogram.chess.Chess