Penguin Pairs - Building JavaScript Games for Phones, Tablets, and Desktop - page 240

Penguin Pairs is a puzzle game in which the goal is to make pairs of penguins of the same color.
The player can move penguins by clicking or tapping them and selecting the direction in which
the penguin should move. A penguin moves until it's stopped by another character in the game
(this can be a penguin, a seal, a shark, or an iceberg) or it drops from the playing field, in which case
it falls into the water and is eaten by hungry sharks. Throughout the different levels of the game,
you introduce new gameplay elements to keep the game exciting. For example, there is a special
penguin that can match any other penguin, penguins can get stuck in a hole (meaning they can't
move), and penguin-eating sharks can be placed on the board. You can run the final version of this
game by trying the example program belonging to Chapter 23. Open the PenguinPairs.html file in
your browser, and you can immediately start playing.