To round 254 to the nearest hundred, look at 254. If the tens place is 5 or above round it to 300, if it is 4 or below round it down to 200. The tens value is 5 so you would round 254 to 300.
I think your teacher is implying for you to explain the function and the "works" behind the game. Maybe talk about the game's programming or the way it's overall structured?