It's very very important to test a video game that is under development, before a game developer puts the game on the market. Bugs have to be fixed. In addition, a video game has to be interesting.
Each video game has each form, each rule and each system. Therefore, means to test each game are different from each other. If a game is First Person Shooting, testers have to play as the soldier of U.S. army and battle with Hitler and Aliens many many time. If a game is a baseball sports game, testers have to play 100 years of pennant race. But, if a video game is resistance training, what are testers doing?
Wii Fit is the hot product of Nintendo. That looks white color board. The board is "Balance Board" that equips the plural stress censors. You may take your weight, play balance games like skiing and do resistance trainings that are Push-Up, Jackknife, Squat and so on for your muscle. Those trainings are mighty tough, so I can not continue to do the training for 1 hour.
But, testers had to test this product before Nintendo put this on the market. They had to do resistance trainings for not their muscle but quality of the game. Their pain was must to tune Wii Fit. Perhaps that's one of the hardest game test in human history.
You may read episodes of the test of Wii Fit at Nintendo web site.