Change the program so that the update rate is twice as fast. This will give you greater resolution on the timing values. To do this you will have to investigate the values which are placed in the OPTION register to set the pre-scaler for the counter divider.

Change the program so that the score given is larger if the player is faster. The way to do this is to subtract the time taken from the longest possible time you think things might take.

Add to the program so that it prints out different messages depending on how fast you are. Try to keep these friendly!