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UK freelance journalist, author
and writer Sean McManus

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Countdown to Christmas with my Scratch advent calendar

05 December 2018


Christmas is coming, so my Scratch advent calendar is once again open, sharing a new project or Scratch resource each day. Visit the calendar here!

The advent calendar includes projects and resources taken from my books:

These all make great gifts for those who enjoy or would like to learn to program in Scratch. Follow the links above for more information on the books including free PDF samplers to give you a taste of the content. Be aware that there is a new version of Scratch launching in January, but the previous versions will continue to be available for download, and most projects should work seamlessly on the new platform.

While we're in the festive spirit, let me tell you about a few other seasonal features on my site. I wrote a Secret Santa program for the Microbit, which you can see in my archive blog post here. You can play my Christmas version of Hangman, Snowman, here and play my Christmas Pairs game here. And Virtual Sean has his Santa suit on! Ho Ho Ho! Happy Christmas, everyone!


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Exploring and customising the Escape game from Mission Python


If you're reading this, you probably know that my latest book is called Mission Python and it shows you how to build a space adventure game. I've added two new bonus resources to the website recently to help you to get the most from the book.

First, there's an empty map template (PDF) which you can use to help you design your own game layout. I've also written an article with tips on customising the game code for your new map. There is a built-in maze generator on the page to inspire your designs too! Get tips and tools for customising the Escape game from Mission Python here.

Mission Python map template

Secondly, in the spirit of all the truly great mags of the 1980s, there is a map of the space station (PDF) that you can use to find your way around, whether you're playing the game or customising it. When I was writing the book, I was mindful of spoiling the surprises by showing you all the cool images and room layouts we have created before you got to experience them in the game. So there are some room layouts shown in the map that haven't been previously published, even in the book screenshots. If you don't like spoilers, maybe play the game a bit before you check the map. For best results, download the PDF map and then zoom in to see each room more clearly. Find out more about the Mission Python space station map here.

Mission Python - map of the space station

Mission Python is available now, and makes an ideal Christmas gift for readers aged 11+ who are interested in coding and want to really get under the skin of how a computer game works.

Not sure whether it's for you? Check out the Mission Python free sampler here.

Find out more about Mission Python here



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Testing the speed of Scratch 3.0 on the Raspberry Pi 3 and the iPad Mini

19 November 2018


As you might know, a new version of Scratch launches in January. This new feature has a lightly redesigned interface, with the Stage on the right (where it was for Scratch 1.4) and a new ability to scroll through all the blocks to find the one you want. The most significant change, though, is that it's been rebuilt from the ground-up using HTML5. That means the same version of Scratch can now be used across a wider range of devices, compared to the previous Flash-based version of Scratch. Raspberry Pi users will be first class citizens in the Scratch community for the first time, able to use the same online version as everyone else.

Scratch 2.0 also works on the Raspberry Pi and now features in the Raspbian download. It's noticeably slower than Scratch 1.4, though, so I was wondering how Scratch 3.0 would measure up.

I created a simple benchmark program that times how long it takes for the cat to walk back and forth across the screen in 1000 movements of 10 steps each. Using a loop of 1000 movements helps to amplify any performance lag so it's easier to measure. Here's the code:

A simple speed test for Scratch

This isn't a perfect benchmark. Some operations (in particular the graphic effects) work more slowly in some versions of Scratch, for example. Because most Scratch programs use sprite movements, this code should give a useful indicator of how they will perform, though. By creating a more complicated benchmark using more features, the risk is that it doesn't capture the typical performance and that some highly optimised (or very slow) commands create a misleading average result. This test is based on the beta as at November 2018, so the launch version of Scratch 3 may be faster or slower, and different software configurations on the devices may also change performance.

I rebuilt the test script in each version of Scratch before testing. My test hardware was:

Obviously, using different devices and more modern devices in the case of the PC and iPad, you may see different results. You can see the code above if you want to try it on your devices, and feel free to share your observations in the comments below.

Drumroll, please! Here are the results, with execution time shown in seconds:

Scratch 3 Scratch 2 Scratch 1.4
Raspberry Pi 3 64.35 70.14 21.7
Windows 8 PC 33 33.32 25.27
iPad Mini 120.1 N/A 27.8

Performance was not always exactly the same, but it was close enough to give a fair indication.

So, the key conclusions are:

It is exciting that Scratch 3 will enable everyone to be part of the vast and growing Scratch community, running the same version of Scratch and enjoying the same features for sharing and discussing projects. There's nothing to stop anyone building their first scripts and programs using Scratch 3 on these devices. As coders progress to more advanced projects and speed-sensitive games, they may prefer to seek out a device with faster performance, depending on the device they are starting with.

For Scratch inspiration, check out my books Coder Academy, Cool Scratch Projects in Easy Steps and Scratch Programming in Easy Steps.

UPDATE: Following a discussion on Twitter, I have new results to share:



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Does the Mission Python game work on a Mac? (and other compatibility questions)

07 November 2018


The game featured in my latest book, Mission Python, is called Escape and sees you solving puzzles to escape a space station on Mars where the air is slowly leaking away. The book advertises the game as working on the Raspberry Pi 3 and Raspberry Pi 2, and on Windows PCs, running Python 3.6. On these platforms, I was able to test both the build of the game and the play-through of the game to completion. The game should also work wherever Pygame Zero runs, but I haven't been able to test it everywhere. I set a high standard for accuracy and testing in my books, and only felt able to actively endorse the platforms we had thoroughly tested.

Some readers have been in touch to ask about compatibility and pass on their advice for other readers. Here's a round-up of compatibility tips and tweaks.

Screenshot from Mission Python

One of the screens you have to dash through in Mission Python.

Does Escape from Mission Python work on the Mac?

Yes! Othelo Vieira has kindly provided installation instructions for the software on his blog. David Weissman has also been in touch to confirm it's working "flawlessly" on his iMac. Many thanks to Othelo and David.

Does Escape from Mission Python work on Ubuntu?

Yes! Matt, also known as RaspberryPiSpy, is using Ubuntu 18 and had previously installed Python 3.6 and Pygame. He found he had to install Pygame Zero using pip3 install pgzero. To run the game he had to use python3 -m pgzero escape.py. Ian Brown confirms this approach using pip3 to install Pygame Zero but says you may hit permission problems, and recommends sudo pip3 install pgzero in that case. If you can't use sudo because your system is locked down, you can try pip3 install pgzero --user. Many thanks to Matt and Ian for testing and sharing their discoveries.

Can you use Thonny with Mission Python?

Yes! Reader Ian Brown says that to do so, you need to put import pgzrun at the very top of the code and then add pgzrun.go() at the very end. He is using Thonny on Ubuntu. Thank you, Ian!

The book uses IDLE, and you might find it useful to stick with IDLE because the color coding will match the colors used in the book.

Does the Mission Python game Escape work with Python 2?

No, sorry. Pygame Zero is only available for Python 3. You can easily download and install Python 3. The instructions are in the book.

Does the Mission Python game Escape work with Python 3.7?

The book recommends Python 3.6 because at the time of writing, Pygame wasn't available for easy installation on Python 3.7. Charles G Smith Jr has been in touch to say he's got the game working on Python 3.7. He writes: "Good News. I was able to get your escape game up and running using version 3.7 of Python. Here is what I did to make your code work with the latest version. I added the import statement of import pgzrun at the top of the program, and I also added the statement pgzrun.go() at the bottom of your program." Many thanks to Charles.

If you're less experienced with Python and/or don't already have it installed, I still recommend using Python 3.6 as described in the book to avoid the need to add extra code into all your listings.

Does the Mission Python game Escape work on older Raspberry Pis?

It doesn't crash, but it runs too slow to enjoy. It does need a Raspberry Pi 2 or Raspberry Pi 3 really.

What screen resolution does the Escape game from Mission Python require?

The game window has a height of 800 pixels, and I have been running it on a screen with a resolution of 1152x864 or higher. However, I did a quick edit to adjust the window height to 700 pixels so it can fit on a screen with a resolution of 1024x768. You may still need to hide the taskbar. You can download the smaller version of Escape here. You will need to rename the extension from .txt to .py, or paste the code into your code editor.

The tallest room in the game is the third room you visit (West Corridor, room 37), so in this version I have taken the height down from 15 to 13 tiles, so it matches the next-largest room sizes. I have repositioned the toxic floor tiles within the new room to avoid them being too close to the bottom exit, which makes them unfairly hard to avoid. I have commented the lines that I changed in this program. Note that in the draw() function, the red box that is used to clear the game area must be resized to avoid overwriting the air and energy bars, and those bars must also be moved up in the AIR section of the program.

Thank you to Ian and Ben Brown for identifying this issue.

What about other compatibility questions?

If you have any concerns, here's a low-risk way to test it works. You can download the free PDF sampler, which includes the installation instructions for Windows and Raspberry Pi together with instructions to get the game working, and you can download the final game code too. You can then test that the game works on your computer before buying the book.

Thank you to everyone who has supported the book so far. I'm excited to see your reviews and customisations!


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Three reasons to download this free PDF sampler of Mission Python

26 October 2018


You can now download a free 56 page sampler of my Python programming book, Mission Python. The book shows you how to build a space adventure game using Python and Pygame Zero.

Here are three reasons you should download this sampler now:

If you have any concerns about software compatibility, this is also a risk-free way to check the software and the final project will work on your set-up. The book provides instructions for the Raspberry Pi and Windows, and readers have been in touch to say they've got it working on a Mac. I'll share more tips on compatibility and getting everything working in my next blog post, but if you have any queries or concerns, feel free to leave a comment below and I'll do my best to help.

Find out more about Mission Python in the launch day blog post here. Discover places you can buy the book here.

Screenshot of the spacewalk simulator

The spacewalk simulator from Chapter 1 of Mission Python



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Mission Python is out now!

16 October 2018


I am delighted to say that my latest book Mission Python has just been published. The book shows readers how to use Python and the Pygame Zero library to build a space adventure game. The game runs on a Raspberry Pi or Windows PC, using free software. We've provided all the images and sounds you need as a downloadable file.

Here's a short video showing the game in action (dramatic music added for the video):

There are several ways to enjoy the book. Some readers will want to play and solve the game first to avoid spoilers, and then use the book to understand how it works. (I have minimised spoilers where possible, but readers might notice some clues when they study the code). Other people might want to build the game, chapter by chapter, either by typing in the code or by using my example listings. At the end of the book, their finished game will be their reward. Still others might want to use the game as a starting point for their own customisations.

I've built in customisation opportunities that should enable every reader to do something unique with the game. Some readers might just want to put their friends' names into the game, and hack the text descriptions. Others will seize the opportunity to design their own room and put it into the game, add a new corridor, or even redesign the map entirely. For graphic artists who are looking for a portfolio project, there's the opportunity to reskin the whole game by replacing our graphics with new image files. More ambitious coders might want to take the engine for the game and replace the maps, descriptions, images and puzzles to create an entirely new game set in a new world. Most chapters include Training Missions, which are small exercises to test your knowledge, with answers at the end of the chapter.

My author copies of Mission Python are here!

When writing the book, I often thought of the kinds of things I enjoyed programming when I was at school. Back then, I was programming an Amstrad CPC computer and I learned a lot from studying listings in magazines and books. I would have loved a book like this to guide me through building a whole game. There are lots of great Python books out there, but the examples tend to be limited to a couple of pages to demonstrate a coding feature. Mission Python provides a single in-depth worked example that allows readers to really get their teeth into a substantial coding project. The program gradually builds, chapter by chapter, in digestible chunks, so readers see the game come together in a similar way to how I did when I first built it.

One of the rooms from the Escape game in Mission Python

The game featured in Mission Python is called Escape. Here is one of the rooms from the game.

You can see some more screenshots of the game in my previous blog post here.

The book is printed in full colour throughout, and produced to the high standards you would expect from the publisher NoStarch. Thanks to the team who worked on this title including the editors Liz Chadwick and Riley Hoffman, NoStarch CEO Bill Pollock, and Rafael Pimenta who did such a fabulous job of creating the game art. Tech editor Dan Aldred helped test the listings, and Daniel Pope created Pygame Zero which I'm using for images and sounds in this project.

I'll be sharing some more insights into the book and some extra resources for readers too over the coming weeks, so keep an eye on this blog or follow me on Twitter for updates. You can find links to order the book here, and more information on the book at its webpage here.


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Mission Python: First screenshots from my new Python coding book

03 August 2018


I am so excited to share the news that my new book Mission Python is now at the printers, and will be available for you to read in September, published by No Starch Press. As you read the book, you'll learn how to build a game called Escape, using Python and Pygame Zero. You can use a Raspberry Pi 2 or 3, or a Windows PC to build and run the game.

In Escape, there is a breach in the wall of the space station, and comms are down. You must establish a safe air supply, and then message for help. As you go about your mission, you'll be challenged to think like an astronaut. You'll have to use the objects you find creatively to solve the game's puzzles.

You might want to play and solve the game first, then use the book to see how it works. Or might prefer to build the game first, then reward yourself with it when you finish making it. Or maybe you'll dive straight into the code listing, and use the book to see how you can customise it with your own maps and puzzles.

Here are some screenshots from the book, showing the fabulous game art created by Rafael Pimenta for this project. You'll be able to download all the art, sound and code files you need.

Screenshot from Mission Python

Chapter 1 uses a simple Spacewalk demo to show you how to draw images on the screen. Space images courtesy of NASA.

Screenshot from Mission Python

The starting room. That computer in the top left can give you a status update.

Screenshot from Mission Python

Dodge the drones. You only have a limited amount of energy.

Screenshot from Mission Python

To open that door you'll need the right access card.

I can't wait for you to see the final book. It's available for pre-order now from many shops, and I'll be happy to take any questions in the comments below. I'll be adding bonus resources to the Mission Python page on my website here. This is my first full-length Python book, but if you're looking for a primer on Python and Pygame Zero while you're waiting for Mission Python to come out, check out Raspberry Pi For Dummies 3rd Edition, which includes two chapters on Python.


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