- The same command line option can"t accidentally be passed twice.
- Accept or reject Xboard engines" features immediately. Some engines (eg. Matacz) fail to initialize properly without this feature.
- Handle cases where an engine fails to start or disconnects almost immediately.
- Option "--protocols" for displaying a list of supported chess protocols.
- Option "--variants" for displaying a list of supported variants.
- Support Atomic, Crazyhouse and Losers variants.
- A castling bugfix for Chess960 and Capablanca random chess.
- JSON format for storing engine configurations.
- Handle non-responding engines better. If an engine runs out of time and then stops responding, it will be properly terminated.
- Games where an engine loses on time do not cause a freeze anymore.