The iconic 2005 Nintendo DS handheld racer relied on traditional button inputs, custom emblems drawn on the touchscreen, and manual 12-digit Friend Codes for online play via the now-defunct Nintendo Wi-Fi Connection.

When a QR code was scanned, it would unlock specific content within the game. The types of content that could be unlocked included:

: A paper on arXiv discusses SD-EQR , a new technique for using QR codes in cryptography. It explores how to hide encrypted messages within the pixelated structure of a QR code—a concept similar to how high-level Mario Kart DS players might use the Emblem Editor to create complex, scannable-looking designs.

Before diving in, consider these risks:

back to top of the page icon