The purpose of this study is to express elements in virtual world with logical constraints using objects in real world with physical constraints. As an example to achieve this purpose, this paper presents an English vocabulary game utilizing game engine Unity and programming language C# along with ARTool Kit, a software library for building Augmented Reality (AR) applications.This game, designed for the purpose of education by aiming at helping students memorize English vocabulary, can be classified as a serious game. Watching the question provided by the game program on the screen, which designates alphabets player can use to assemble into a word, the player arranges the cardboard boxes with alphabets on it in the real world. Through the camera, the AR program detects the arrangement and position of the markers which are the alphabets on the boxes. Then, the game program judges whether the arrangement is the correct English word. This game expresses the game objects in the game program using cardboard boxes in the real world.