Is this QR code in Fez useful?

Solution 1:

The 16-cube area is the ancient version of the temple/science warp zone. That QR code was under construction long ago, but it now appears "fully realized" on the same wall in the temple/science warp zone. So it can be completed—indeed, it has been.

If you're curious, the QR code links to...

text: "RT RT LT RT LT LT LT RT" (which triggers an anticube, as shown above)

This is a higher resolution of the screenshot, from the PC gersion of the game:

I have then extracted the QR code, converted it to black and white, removed Gomez and some dust, and applied a median filter. This is the complete QR code, which you can scan on a website.

Solution 2:

I finished the game and found the completed QR code. After I scanned it it's #F0493E, which is a hex color for a shade of red. I want to say it has something to do with the 3 red rooms and the 3 missing pieces of the heart puzzle...but I have no way of proving that.

Solution 3:

The code translates to RT RT LT RT LT LT LT RT. If you push d d a d a a a d you get an anticube