This is a Java Applet I submitted to a high school project contest in 1997. It plays the Master Mind game against a human player and guesses the combination the other player thought of with the minimal number of guesses.
The source code for the applet is available in this repository. Unfortunately, modern browsers do not suppor Java Applets any more, but the repository contains instruction describing how to run the applet in a modern browser.
The allowed colors are empty, blue, red, black, white, green, and yellow.
Back then, I also developed a C++ version, the source code and an MS-DOS executable of a C++ version (in German) in this repository.
The program basically computes the expected information entropy of the answers for each possible question and then chooses the question with the highest value.
More recently, I re-implemented the algorithm in Julia and in Go. The code in both languages uses multi-threading to speed up the calculation.