𝐓𝐡𝐞 𝐟𝐢𝐫𝐬𝐭 𝐠𝐚𝐦𝐞 𝐦𝐲 𝐤𝐢𝐝𝐬 𝐚𝐩𝐩𝐫𝐨𝐯𝐞𝐝

Written by marcelpetrick on July 23, 2026

I like good turn-based offline games. Recently, the kids brought home one that I won’t name here because my GitHub Pages–backed browser game is a shameless copy.

If you want to play it (free and safe): https://marcelpetrick.github.io/recognizer/

𝗧𝗵𝗲 𝗿𝘂𝗹𝗲𝘀 𝘁𝗮𝗸𝗲 𝘁𝗲𝗻 𝘀𝗲𝗰𝗼𝗻𝗱𝘀 𝘁𝗼 𝗲𝘅𝗽𝗹𝗮𝗶𝗻: 𝘛𝘸𝘰 𝘤𝘢𝘳𝘥𝘴. 𝘌𝘪𝘨𝘩𝘵 𝘴𝘺𝘮𝘣𝘰𝘭𝘴 𝘦𝘢𝘤𝘩. 𝘌𝘹𝘢𝘤𝘵𝘭𝘺 𝘰𝘯𝘦 𝘮𝘢𝘵𝘤𝘩. 𝗙𝗶𝗻𝗱 𝘁𝗵𝗲 𝗺𝗮𝘁𝗰𝗵 𝗳𝗮𝘀𝘁𝗲𝗿 𝘁𝗵𝗮𝗻 𝘆𝗼𝘂𝗿 𝗺𝗮𝘁𝗲𝘀.

It is super simple, but pattern matching requires concentration, and you have to be quick. 𝗜𝘁’𝘀 𝗴𝗿𝗲𝗮𝘁 𝗳𝘂𝗻 𝗲𝘃𝗲𝗻 𝗮𝘀 𝗮 𝘀𝗶𝗻𝗴𝗹𝗲 𝗽𝗹𝗮𝘆𝗲𝗿 with a local high-score list.

Building it raised three useful questions:
* 𝗛𝗼𝘄 𝗱𝗼 𝘆𝗼𝘂 𝗴𝘂𝗮𝗿𝗮𝗻𝘁𝗲𝗲 that rule across all 𝟏,𝟓𝟗𝟔 possible card pairs?
* 𝗛𝗼𝘄 𝗱𝗼 𝘆𝗼𝘂 𝘁𝘂𝗿𝗻 a shared game into a good single-player challenge?
* 𝗛𝗼𝘄 𝗺𝘂𝗰𝗵 𝗶𝗻𝗳𝗿𝗮𝘀𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗲 does a small browser game actually need?

The mathematical part uses a finite projective plane. 𝗧𝗵𝗲 𝘁𝗲𝘀𝘁 𝘀𝘂𝗶𝘁𝗲 𝘃𝗲𝗿𝗶𝗳𝗶𝗲𝘀 𝗲𝘃𝗲𝗿𝘆 𝗽𝗼𝘀𝘀𝗶𝗯𝗹𝗲 𝗰𝗮𝗿𝗱 𝗽𝗮𝗶𝗿.

The product stays deliberately small: 10, 20, or 50 cards, a timer, and local high scores. 𝘕𝘰 𝘢𝘤𝘤𝘰𝘶𝘯𝘵𝘴. 𝘕𝘰 𝘨𝘭𝘰𝘣𝘢𝘭 𝘳𝘢𝘯𝘬𝘪𝘯𝘨𝘴. 𝘕𝘰 𝘣𝘢𝘤𝘬𝘦𝘯𝘥.

𝗔 𝘀𝗶𝗱𝗲 𝗻𝗼𝘁𝗲 𝗳𝗼𝗿 𝘁𝗵𝗼𝘀𝗲 𝗶𝗻𝘁𝗲𝗿𝗲𝘀𝘁𝗲𝗱 𝗶𝗻 𝘀𝗼𝗳𝘁𝘄𝗮𝗿𝗲 𝗱𝗲𝗹𝗶𝘃𝗲𝗿𝘆
I also used the project as a compact, end-to-end SDLC example: written requirements, scope, and acceptance criteria; separated and testable domain logic; versioned storage with migration handling; unit, component, browser, mobile, and accessibility tests; formatting, linting, type checking, and build gates; locked dependencies with automated updates; and repeatable PWA deployment through GitHub Actions and GitHub Pages.

𝐈𝐟 𝐲𝐨𝐮 𝐭𝐡𝐢𝐧𝐤 𝐲𝐨𝐮 𝐚𝐫𝐞 𝐪𝐮𝐢𝐜𝐤𝐞𝐫: 𝐩𝐥𝐚𝐲 𝐚𝐧𝐝 𝐩𝐨𝐬𝐭 𝐲𝐨𝐮𝐫 𝐬𝐜𝐨𝐫𝐞 🤗

Got myself a micro:bit :)

Written by marcelpetrick on March 12, 2018

After gaining some experience with the Calliope mini I was eager to have look over the edge of the plate and found the Sino:bit with an even bigger matrix of 144 LED. BUT: there is still the humble predecessor, the BBC micro:bit. A very original and clever project to get ALL children at school started. At a price of around 17€ what can go wrong? Give ten children one for free and even if just one turns into a programmer/software-developer (or just gains a bit insight how their favorite electronic gadgets work), then it was worth but. But what do I say as german citizen. Hello Flugtaxi :’|
I plan to get my feet into the cold and muddy waters of robotics. Of course, assembling the :move mini with the bulldozer add-on will be nothing great, but I’ve craved to find out how to control a servo and how to put some life into the boring aspects of programming. Just kidding. But blinking LED and measuring values is nice, but … I want to build my own cat-feeder. Or at least something which moves and blinks to keep them a bit attracted.
And: the micro:bit and Calliope mini feature both Bluetooth-radios, so connecting them shouldn’t be a problem.
Another advantage: somehow the given libraries for the micro:bit are more advanced and diverse than the Calliope’s, could be due to the release in 2015 versus 2017. Also: micro:bit features microPython. C not ..

My first idea was to create a stress-test. Play a bit around with the buttons and the “run in background”-feature. Still not heating properly and fast enough.
Code is visible on my micro:bit-repository on github. Just like the one for the Calliope. Suggestions how to make the processing unit glow are heartily accepted 🙂

Let us get coding. Somehow I like the enviroment with blocks and the possibility to switch to Javascript. Not my favorite dialect, but … sometimes you have to embrace what is given to you <3

20 min-project of today: creepy squirrel

Written by marcelpetrick on December 1, 2017

Had in mind to play around with the “make LED shine directly via PIN”-feature of the Calliope Mini. Worked, nice 🙂
Actually for both “eyes” it is randomnly picked if they shall light up (and down) separately, but the GIF can can last just 3 seconds.

let ledpowerinverted = 0
let pin2 = false
let pin1 = false
basic.forever(() => {
   pin1 = Math.randomBoolean()
   pin2 = Math.randomBoolean()
   for (let ledpower = 0; ledpower <= 1023; ledpower++) {
       if (pin1) {
           pins.analogWritePin(AnalogPin.P1, ledpower)
       }
       if (pin2) {
           pins.analogWritePin(AnalogPin.P2, ledpower)
       }
       basic.pause(2)
   }
   for (let ledpower2 = 0; ledpower2 <= 1023; ledpower2++) {
       ledpowerinverted = 1023 - ledpower2
       if (pin1) {
           pins.analogWritePin(AnalogPin.P1, ledpowerinverted)
       }
       if (pin2) {
           pins.analogWritePin(AnalogPin.P2, ledpowerinverted)
       }
       basic.pause(2)
   }
   basic.pause(500)
})

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let ledpowerinverted = 0

let pin2 = false

let pin1 = false

basic.forever(() => {

pin1 = Math.randomBoolean()

pin2 = Math.randomBoolean()

for (let ledpower = 0; ledpower <= 1023; ledpower++) {

if (pin1) {

pins.analogWritePin(AnalogPin.P1, ledpower)

}

if (pin2) {

pins.analogWritePin(AnalogPin.P2, ledpower)

}

basic.pause(2)

}

for (let ledpower2 = 0; ledpower2 <= 1023; ledpower2++) {

ledpowerinverted = 1023 - ledpower2

if (pin1) {

pins.analogWritePin(AnalogPin.P1, ledpowerinverted)

}

if (pin2) {

pins.analogWritePin(AnalogPin.P2, ledpowerinverted)

}

basic.pause(2)

}

basic.pause(500)

})

applied science ;3

Written by marcelpetrick on October 28, 2017

The surface-temperature of an average ~furry lazybutt~ housecat is 24°C 😀

For this important experiment you need: a Calliope Mini, a computer science-degree and too much free time ;’)
Just kidding, the code is quite simple:

input.onButtonPressed(Button.A, () => {
    music.playTone(262, music.beat(BeatFraction.Whole))
    basic.showString("" + input.temperature() + "°C")
})

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input.onButtonPressed(Button.A, () => {

music.playTone(262, music.beat(BeatFraction.Whole))

basic.showString("" + input.temperature() + "°C")

})

Jubilate deo!

Written by marcelpetrick on July 4, 2017

Ok, today arrived the Calliope mini and after doing all my chores I spent one hour tinkering with the tiny star 🙂
An improved version of one of the suggested projects: the first part of “Ode to joy” from Beethoven together with a blasting animation. Start by pressing “A”.

input.onButtonPressed(Button.A, () => {
    basic.showLeds(`
        . . . . .
        . # . # .
        . . . . .
        # . . . #
        . # # # .
        `)
    music.playTone(330, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(330, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(349, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(392, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(392, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(349, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(330, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(294, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(262, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(262, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(294, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(330, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(330, music.beat(BeatFraction.Quarter))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(294, music.beat(BeatFraction.Eighth))
    music.rest(music.beat(BeatFraction.Half))
    music.playTone(294, music.beat(BeatFraction.Half))
    for (let i = 0; i < 4; i++) {
        basic.showLeds(`
            . . . . .
            . . . . .
            . . . . .
            . . . . .
            . . . . .
            `)
        basic.showLeds(`
            . . . . .
            . . . . .
            . . # . .
            . . . . .
            . . . . .
            `)
        basic.showLeds(`
            . . . . .
            . . # . .
            . # . # .
            . . # . .
            . . . . .
            `)
        basic.showLeds(`
            . . # . .
            . # . # .
            # . . . #
            . # . # .
            . . # . .
            `)
        basic.showLeds(`
            . # . # .
            # . . . #
            . . . . .
            # . . . #
            . # . # .
            `)
        basic.showLeds(`
            # . . . #
            . . . . .
            . . . . .
            . . . . .
            # . . . #
            `)
    }
    basic.showLeds(`
        . . . . .
        . . . . .
        . . . . .
        . . . . .
        . . . . .
        `)
})

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input.onButtonPressed(Button.A, () => {

basic.showLeds(`

. . . . .

. # . # .

. . . . .

# . . . #

. # # # .

`)

music.playTone(330, music.beat(BeatFraction.Quarter))