Those who claim running 1440*900 on MBPR in games that just look exactly like the non-retina version is just pure lying...
Tried both running on 1440*900 / 1680*1050, and all of them appears to be more blurry on Retina screen than non-retina.
No matter how hard people trying to claim, this problem already been discussed and also appear on both new iPad and iPhone 4 when it came out...
It's there, no matter how hard people trying to deny.
Did you or anyone else do side-by-side comparison? I have to honestly admit that I don't have a RMBP at my disposal, so I can't do it. The experiment would be simple: load the same game with two machines, at the same resolution (native for non-retina machine), walk away for 5 minutes, then come back and inspect the images. Better yet, make some close-up high-res pictures. My prediction is that none will be blurrier than the other one. A 'pixel' on the retina using 1440x900 resolution (e.g. block of 2x2 real pixels) has the same physical dimension ans a pixel on a non-retina. I can't imagine that these two will look differently. Of course, it possible that the retina pixels are not uniformly lit, then it will indeed be blurry.