App Inventor

Chapter 3. MoleMash

This chapter shows you how to create MoleMash, a game inspired by the arcade classic Whac-A-Mole, in which mechanical critters pop briefly out of holes, and players score points by whacking them with a mallet. MoleMash was created by a member of the App Inventor team, nominally to test the sprite functionality (which she implemented), but really because she is a fan of the game.

When Ellen Spertus joined the App Inventor team at Google, she was eager to add support for creating games, so she volunteered to implement sprites. The term, originally reserved for mythological creatures such as fairies and pixies, emerged in the computing community in the 1970s, where it referred to images capable of movement on a computer screen (for video games). Ellen first worked with sprites when she attended a computer camp in the early 1980s and programmed a TI 99/4. Her work on sprites and MoleMash was motivated by double nostalgia—for both the computers and games of her childhood.

What You’ll Build

For the MoleMash app shown in Figure 3-1, you’ll implement the following functionality:

Figure 3-1. The MoleMash user interface

• A mole pops up at random locations on the screen, moving once every second.

• Touching the mole causes the phone to vibrate, the display of hits to be incremented ...