Car-Fu is a special move that characterizes the Wii game Speed Racer, based on the popular animated series and movie. Developers thought it would very easy for players to pick up and execute and that players would be excited to use it. During user testing sessions, however, they found players were not using the Car-Fu move at all. The problem was successfully fixed by showing players Car-Fu happening within the game: in a subsequent build of the game AI opponents would do more Car-Fu on one another and against the player as well. By providing players with this reminder, they then realized that they too could perform the move. The solution also served as a way to increase the challenge, because when a player was attacked, it would instantly trigger the desire for revenge and prompt further engagements. When they realized what they could then do, the enjoyment of the game simply rocketed.
Griffiths, G. (2009). Practical game playtesting: A Wii-based case study. Gamasutra Feature. Retrieved here: http://www.gamasutra.com/view/feature/3894/practical_game_playtesting_a_.php