KeyChainino 144

A tiny game console that lives on your keys.

144 real LEDs, two buttons and a coin cell that lasts for months. 17 games are already inside: pick one, play, put it back in your pocket.

And if one day you want to change a game, or write your own, you can. With Arduino.

Buy it · 27€ Play it here first

Only a few pieces of this batch are left. We can't promise a restock: if you've been waiting, now's the time.

A KeyChainino 144 in the palm of a hand, with a red LED smile lit on its 12 by 12 LED matrix — 4.8 × 2.5 × 1 cm

LEDs14412 × 12, real LEDs. No screen.

Games17Each one saves your high score.

BatteryCR2032One coin cell lasts for months.

ButtonsA · BThat's all you need.

SourceOpenGPL-2.0, all on GitHub.

Play it here

Try it before you buy it.

This is not a video. It's the real KeyChainino 144 firmware, running in your browser: same 17 games, same menu, same two buttons.

Press A and B to choose a game, both together to play. On a computer, the keyboard works too.

Keyboard←Z= A→X= BSpace= A+B

Inside

17 games. Already inside.

The first KeyChainino, back in 2015, had one game: a brick breaker. Today there are seventeen, and each one keeps your best score, even when you change the battery.

Bricks
Snake
Blocks
Invaders
Tennis
Tower
Frog
Flap
Racer
Echo
Jump
Catch
Whack
Dice
Life
Muncher
Steroids
Yours?

What it is not

It's not a smartphone.

No colors. No sound. No screen. Only 144 red LEDs and two buttons.

I know, it sounds like a limit.

But that's exactly why it works. You take it out while you wait for the bus, you play for two minutes, and you put it back in your pocket. The battery lasts for months because there's nothing else to feed.

And when it sleeps, it really sleeps: it wakes up only when you press A and B together. So it won't turn on by itself in your pocket.

New · Pictures

Your child draws it. The KeyChainino shows it.

I made Pictures for my daughter. On the computer there's a big KeyChainino: she taps the lights to draw, presses the rocket, and a second later her drawing lights up on the real one.

A and B flip through the pictures. Both together, and the picture comes alive.

How it works with kids →

On my KeyChainino

Open source

Open it up. Change the game.

Everything inside the KeyChainino is on GitHub: the games, the LED driver, the tools. And there's no library to install: every sketch folder has everything it needs.

To upload a sketch you need a programmer. A USBasp costs a few euros. Or you can use an Arduino UNO you already have in a drawer :)

# the 17 games, from the terminal
avrdude -patmega328p -cusbasp -Pusb \
  -U lfuse:w:0xe2:m -U hfuse:w:0xd7:m \
  -U efuse:w:0xff:m \
  -U flash:w:KeyChainino_v144_multigame.hex:i

Three KeyChaininos side by side on a wooden table

Where it started

It all started at a bus stop.

I was waiting for the bus, playing with my keys, and I thought: why can't my keychain do something fun?

In 2015 the first KeyChainino was born: 30 LEDs, an ATtiny84 and one game. Then came the THT kit, to solder yourself, the V3 with 64 LEDs, and now the 144.

The idea hasn't changed since the first day. A tiny thing to play with in the boring moments. And open, so you can make it yours.

Alessandro

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April 2025