Concentration is a classic card game that is played by laying out cards in a grid facing down. The deck is full of pairs of matching cards. On each turn, you get to flip over two cards. If they match, you leave them face up. If they don’t match, you flip them back over. The goal is to find all the pairs in as few turns as possible—or to find the most pairs if you’re playing with multiple people. The game has been recreated digitally many times, and virtually every computer and video game console ever made has some version of it available. You can also make your own hardware version of the game using an Arduino and RFID cards.
The only hardware you need for this build is an Arduino board (any model will work), an RFID reader module, compatible RFID cards, and an 8×8 LED matrix. Some additional LEDs are helpful to use as status indicators, as is a simple buzzer. You can use as many RFID cards as you’d like, so long as you use an even number. You’re really only limited by the relatively small number of unique patterns that can be reasonably recognized by a person and displayed on the LED matrix. You can purchase RFID cards for well under a dollar each, so it’s affordable to build a pretty substantial deck.
The provided code has you begin by setting up the game. To do that, you simply scan each card you’re planning on playing with. The code running on the Arduino will automatically group the cards into pairs. To start the game, you simply re-scan any of those cards. When you start playing, scanning a card will show a unique shape on the LED matrix. When you scan the next card, it will display that shape. If they match, you can set aside those two cards. If they don’t, you put them back. Rinse and repeat, and you’ve got an electronic version of Concentration!