* You can choose from 20 levels of difficulty.
* You can have AI play against each other.
* You can change players or difficulty during the game.
* You can have a folding machine.
* You can continue the stopped game because the app is closed.
* Notation can be saved and restored.
Some of the artificial intelligence of this app is a modification of the Chinese long-term AI engine at http://sourceforge.net/projects/xqwizard/, and the source code after the modification is at http://blog.naver.com/ohjsn .