Whack-a-mole is a popular arcade game invented in 1976 by Aaron Fechter of Creative Engineering, Inc.. The adaptation of this game to the mirco:bit has been fully designed and implemented by one of our students during a computer science lesson!

The aim of the game is to use a mallet to strike a mole within a certain time. Moles randomly appear for a short time above a hole.

As we will be using the micro:bit, our game will consists of two holes and two moles. The player will strike a mole by pressing the A or the B button on the micro:bit depending on whether the mole appears on the left or the right hand side of the LED screen.

Look at the picture below. The ! represents a mole on the left hand side, The player has less than 1 second to whack this mole by pressing the A button.

The code

Code Review

• Randomly display a mole to either the left or the right of the screen?
• Check, if the left mole is displayed, that the user has pressed button A and if not ends the game?
• Check, if the right mole is displayed, that the user has pressed button B and if not ends the game?
• Allow a maximum of 1 second for the user to whack a mole? If the use exceeds this delay, the game should end.

Extension Task #1:

Tweak this code so that both moles can appear at the same time. In this case the player needs to press both buttons A and B simultaneously to strike both moles otherwise they lose.

When the user strike both moles simultaneously they should get a 5-point bonus added to their score.

Extension Task #2:

To start with the delay should be set to 1000ms, it should then decrease to 900ms, then 800ms, 700ms, etc…

Tip: Use a variable to store the value of the delay. Initialise this variable to 1000ms.

Solution...

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Have you ever seen a lightning flash or heard the thunder of lightning and wondered how close you were from the lightning strike? Have you noticed that there often was a delay between the flash of light and the clap of thunder when a lightning occurs?

It is possible to calculate the distance to a lightning strike by counting the seconds between the lightning flash and the sound of thunder.

When lightning strikes, the first thing you see is the flash of light which you can see instantly. This is because light travels at a very high speed (Speed of light = 300,000 km/s). At the same time a clap of thunder is created. However, in the air a sound wave does not travel as fast as light, so it may take a few seconds for this clap of thunder to reach you. This depends on how far you are from the lightning.

Look at the following diagram and check the formula of speed. Bear in mind that the speed of a sound wave in the air is 340 m/s.

Your Challenge

1. Press the A button of the micro:bit when they spot a lightning flash.
2. Press the B button of the micro:bit when they hear the thunderstorm.
3. Display the distance (in meters) from the lightning strike using the LED screen.

Solution

We will complete this project in three main coding blocks.

First, let’s display an arrow pointing left to invite the user to press button A when they see a lightning strike.

Then we will record the exact time (in milliseconds) as to when button A was pressed and store this number in a variable called lightning. We will also display an arrow pointing towards button B.

Let’s now record the time (in milliseconds) when button B is pressed using a variable called thunder. We can then use these two timestamps to work out the time delay between the lightning strike and when the thunder was heard. Using the distance = speed x time formula, we can then workout and output the distance in meters from the lightning strike:

Solution...

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During a gold rush, gold miners use different techniques to find traces of gold hidden in the ground. One technique that miners use is gold panning. It consists of scooping some gravels and clear water in a pan which is gently agitated until small gold nuggets sinks to the bottom of the pan and can be handpicked.

For this challenge the pan will be the micro:bit. A LED light will represent a gold nugget. The aim is to tilt the micro:bit slightly to detect and pick up the gold nugget.

We will be using the built-in accelerometer sensor to detect in which direction the microbit is being tilted.
Every time the player (miner) will pick a gold nugget a new one will randomly appear on the 5 x 5 LED screen.

Complete Code

Code Review

• Can you identify the block of code used for the micro:bit to detect if it has been tilted to the left?
• Can you identify the block of code used for the micro:bit to know when the miner has picked up a gold nugget?
• Can you explain how does the micro:bit decide to stop the game by running the last block to display the Game Over message?

Extension Task

Ideas to get started

1. You could use a variable called “timer” and set it to 60000ms.
2. You could decrement your timer variable when the game is paused.
3. You will have to change the condition of your while loop: Instead of while score<10, use while timer>0.
4. Make sure that you display the final score at the end of the game.

Solution...

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