Tried the trial of DM and again, not sure what the issue is. It played like any other arcade shooter I've tried on smartphones (i.e. Space Deadbeef for iOS).
As for peestandingup, I think I figured out how you were doing that. I was able to replicate your issue by carefully gently rubbing the screen more or less exactly between Live Tiles. This seems to create a behavior that mimics what I see happening in your video.
However, I have to strenuously disagree that this is a "screen responsiveness issue." As others have said, that's a feature, not a bug. If you touch a Live Tile, it opens. If you hold down a Tile, it brings up the move/un-pin interface. If you swipe your finger more than an inch or two in either direction, the screen scrolls. What you were doing is a strange test as I can't see how it proves or tests any aspect of the phone at all, other than showing how precise the screen actually is. THe ability to accurately touch BETWEEN Live Tiles is impressive, but I can't fathom how it shows something is wrong with the screen.
With a light touch on an actual Tile, the screen responds perfectly. With a long press, it does what it's supposed to. On a swipe, it scrolls. Only when you perform the honestly somewhat strange rub that you were demonstrating does it not respond. And that's probably because it's not supposed to respond to that kind of touch. There are about a million and one jokes that could be made about our discussion in this thread, so hopefully nobody comes along and makes them.
I'm not new to WP, and I can honestly say that I've never seen this before on any device no matter where on the screen my thumb was. If my thumb was between a live tile at first in this particular video, then so be it. But you can see my thumb moving outside of that area too. And like I said, it was like that all over the OS, inside the browser, etc. This is just the video I took & I played with 3 of them that behaved the same way.
And I don't think that type of subtle touching of a touchscreen device is "strange" at all. I do it all the time in browsers, in apps, reading text, etc. Everything's not supposed to be a swipe or a flick. It should follow the movements & do what your thumb/fingers are doing. My other phones do, why not this one??
But I'm not gonna get into that. Seems like a silly argument & nit picky.