Create digital time (Only show Min and Sec)

I would like to create a digital time which only show min and sec. This time is use in a game in order to test the users speed and accuracy. When the user finished the game, the time will stop and then have to check the time user has spent to finish the game. So, if the user manage to finish the game before 10 min, will get 100 points. If is between 10 and 15 min, will get 90 points and so on. I hope someone can help me because it’s quite urgent. Thanks!