Core Functionalities

1. A player must be able to enter their name before the start of a game run. (You may load the player's name from the GameKit API if you wish. This extra work is not required.)
2. A game timer shall be displayed and it must count down continuously in one-second intervals. When the timer reaches zero, the game stops.
3. A score shall be displayed. It shall be zero initially and shall be updated every time the player successfully “pops” a bubble.
4. The default timeframe for a game is 60 seconds, i.e. the game timer starts from 60 seconds and counts down to 0. This number shall be adjustable in the app settings.
5. The maximum number of bubbles displayed on the screen is defaulted to 15, i.e. there shall be between 0 and 15 bubbles shown on the screen at the same time. This number shall be adjustable in the app settings.
6. The app randomly decides how many bubbles (up to the maximum allowed bubble number) shall be displayed on the screen at a time. The bubble colour is decided according to the Probability of Appearance in Table 1.
7. Bubbles shall be displayed at random positions on the screen with the following restrictions:
8. The entire bubble shall be displayed within the screen. There shall not be any bubble with some parts off the screen once it has fully appeared.
9. No two (or more) bubbles shall overlap each other.
10. When a player touches a bubble, the bubble shall be removed from the screen and the corresponding game points shall be added to the overall score. For example, if the green bubble in Figure 1 was touched, it shall disappear and the score shall increase by 5 game points. If two or more bubbles of the same colour are popped in a consecutive sequence, the bubbles after the first one will get 1.5 times their original game points. For example, if two black bubbles were popped one after the other, 25 (10 + 1.5 * 10) shall be added to the total score. Round to the nearest integer if necessary.
11. The app shall refresh bubbles displayed every game second. That is, after every game second, the app shall randomly remove a number of bubbles (do not include the bubbles that have been popped by the player) and replace them with another set of randomly positioned bubbles. There may be more or less bubbles on the screen compared with the previous game second subjected to the restrictions in 5 and 6. In this case, "random" means chosen by the program, not the user. So you have a lot of discretion in placement of new bubbles and selection of old bubbles.
12. When the game stops, the player’s score shall be saved in a persistent file (or database) that contains all players’ names and their highest scores.
13. At the end of the game, a high score board shall be displayed with the names and scores of the highest ranking players. (See Figure 2)

Extended Functionalities (please do not start on these until finishing CFs)

1. In addition to core function 7 and 9, displayed bubbles shall move and go off the screen if they are not removed earlier. Their moving speed shall increase as the game timer counts down. You decide the rate of change with respect to the game timer.
2. Animations of game state transitions. For example, one of:
3. Flashing count down 3, 2, 1 start at the beginning of play
4. Bubbles shrinking, growing, or flying away when removed or tapped
5. Score changes or combo lengths displayed with animations in response to taps
6. The highest score in the scoreboard shall be displayed during gameplay.
7. Any cool and useful features that you can think of.