Zhongwen is a Chinese language learning aid that quizzes the player in one of three ways: by word meaning, by pronounciation or by character.
There are varying levels of difficulty - rated by how much a particular word is used in everyday life. Common words appear in the easiest levels, whereas the more obscure words only appear in harder levels.
The player is in all three cases shown something and must chose which of the four presented options is correct. For example, if shown a character and its pinyin pronounciation, the four options shown question the player as to the word's meaning.