Wait, the DS version of Chrono Trigger was actually a remake, not just a port. It had new gameplay elements, like multiple endings, a remake of the game engine, and maybe a new overworld. The QR code could have been used for a special feature, like a digital code for a trial or a related item. I can't recall the exact details, so maybe I need to look this up. Let me check a few sources quickly.
I need to present the information clearly, but acknowledge if the details are not entirely certain. The user might be looking for historical information, so it's better to state the possibilities if the exact use is unclear. Also, considering the current relevance, since Chrono Trigger is a retro game, the QR code might not work anymore. So, I should note that and suggest checking archives or communities for further info. chrono trigger ds rom qr code
Upon checking, some references mention that in the Japan-only release of Chrono Trigger DS, the packaging included a QR code that led to a downloadable trial version or additional material. It's possible it was a promotion for another game or a trial of Chrono Trigger DS itself. However, I'm not entirely sure. Another angle is that the QR code might have been used in promotional materials outside Japan, but that's speculative. Wait, the DS version of Chrono Trigger was