Put text on the screen, such as the “Score:” and “Round:” labels. Some of this text changes over time, for example the score, which increases when the player scores points.
Put a slider on the screen and make it go between the values 1 and 100.
Read the value of the slider after the user presses the Hit Me button.
Generate a random number at the start of each round and display it on the screen. This is the target value.
Compare the value of the slider to that random number and calculate a score based on how far off the player is. You show this score in the alert popup.
Put the Start Over button on the screen. Make it reset the score and put the player back into the first round.