I am a fan of applying gaming principles (gamification) but I am also a fan of playing games to learn. While most games are not specifically designed for instructional purposes and many instructional games are not much more than a dressed up worksheet there is much to learn from games that are not specifically designed to teach.
If students played the game "cut the rope" different levels help them to understand different things. Physics principals are obvious but as I am playing this one particular level involving a rocket that needs to be launched in a particular direction, this could teach several geometry concepts. Radius, tangent line to a circle and more.
By first giving students a common shared experience such as playing cut the rope the teacher can use this as an ongoing analogy throughout the school year. If students already have practice playing the game then the teacher can demonstrate levels of cut the rope at various intervals as an application of concepts and students can easily relate and understand the application. This also gives students something productive but fun to do if they finish a task early. Instead of disturbing their neighbor, they can quietly be engrossed in a puzzle solving game.