A main objective in teaching English as a foreign language (EFL) is to enable students to communicate effectively in many situations and contexts. This involves being able to control a wide range of language functions, which are how speakers use language for requesting, congratulating, apologizing, complaining, consoling, and promising, among many other functions. The author was relieved when she found that the popular game of "Sudoku" offers an ideal, authentic context for incorporating modal verbs and colloquial expressions to teach the useful language functions known as "confident hypothesizing" and making "logical conclusions." Playing Sudoku provides a meaningful context for many learners to get actively involved in generating, at a very high frequency, the functional language of confident hypothesizing and concluding. Likewise, the colloquial expressions and language of challenge come so naturally in the context of a game that one forgets how highly form-focused the language of play actually is. (Contains 1 figure and 1 table.)