The King of OX is an addictive puzzle game developed by WestRiver for Android users. The game is about selecting either "O" or "X" as fast as possible. It is designed to test your reflexes and is incredibly simple, yet addictive. The game is set in the background of a teacher grading a student's math test.

The game has a simple and addictive gameplay where you select either "O" or "X" according to the right answer of the math test. Once you start playing, it's hard to put it down. The game also has a great social gameplay feature that allows you to compete with your Facebook friends. You can also form teams with your friends or family to make a better record. The game has a global, country, daily, and local high score system that adds to the fun.

If you are looking for a fun and addictive puzzle game, then The King of OX is definitely worth trying. You can also try other games like "1to50" or "Challenging Times table" if you enjoy this game.