How is a lesson like a game?

In a game there is a clear end point so you know if you're winning or losing. 
In a lesson you have goals or aims to achieve and you only know if you're achieving them if you know how to measure your students' progress. 
(This sounds obvious, but it isn't.  How many times do teachers ask "Do you understand?" and everybody says yes even if they haven't understood?)

In a game you have core mechanics which is what you're actually doing from moment to moment, whether it's kicking a ball to a teammate, moving a chess piece, or clicking a mouse. 
In a lesson you need to consider what the students are doing from moment to moment and how you know they're doing it right.  For example, what are the stduents doing if the teacher is talking at the board?  Most teachers would want to say the students are listening...but how do they know?  The students need to do something to prove they're listening, whether it's answering questions, taking notes or whatever.

Most teachers have an idea of their end point because they have to write it in their syllabus.  The mistake is that the end point is often not written from the students point of view.  For example, there is a difference between "we will do the grammar exercises on page 23" (teacher's aim) and "the students will attempt to correct common mistakes involving the past tense" (students' aim).

Few teachers have any idea of the core mechanics of their lesson, which is why the only way they know how well students have understood is by giving them a test.  Which they fail.  And the teachers wonder why.

When you plan your lessons, how do you think about your end points and your core mechanics?