I'll reply top to bottom. Appreciate your detailed answer
Ignore ICC+Gamma: so I was right and Windows is a separate calibration. Not because games have in-game options for it, but because games open their own OGL/DX buffer and it's up to the game to allow settings and up to the driver maker to provide adjustments beyond that. OSD works of course, but most monitors are limited++ in that regard...
Vertical lines: I found that it's even more noticeable when playing video. Hz doesn't matter. So that's a good test to check your monitor. I wouldn't say it's very distracting in games. But it's there. It wasn't on my 1080p. Don't know what it's for. Maybe it even dithers the image so that it's slightly improved. I didn't have the vertical line problem when scrolling in browsers that others have mentioned, or the Vertical Scroll test (as I mentioned in the PM after that).
Inverse ghosting: I had good results with ULMB doing its job and contour shadows disappeared. With my i7+980 PC I couldn't get good results at 60 FPS/higher Hz, and then if I like strafed WA and looked halfway to the ground, the ULMB invented some wave patterns on the ground. Quite weird.
G-Sync did its job too and I've found out through this "what kind of blur I want to fix". It's basically the normal blur from the standard black-to-white-timing of the pixels. And I can really only fix that by creating resolutions with Hzes matching the FPS cap I want in the game. At 59 cap/60 Hz, I get the normal stagger when looking around and only motion blur added in the game alleviates it.
My conclusion is to not bother with the G-Sync. Just set the best options you can and cap, and turn ULMB on. This yielded best results for me. (Well obviously if you're getting 40 fps in some game, by all means use it until you can upgrade the gfx card. That's the use as far as I can see from my tests.)
Flat midrange: The first thing I noticed was this screen had excellent detail in medium to black luminance range. I.e. most games are set in depressing, dark environments to "make them scary/exciting" and it was very nice to suddenly see crisp detail (although I may not have calibrated my older TN panel to specifically target that previously). Very nice.
But in games, there's often distance fog. This brings colors of objects at a medium-long distance together and towards medium gray. Trees at that distance were notedly more flat and devoid of detail than on my older TN panel.
But I still haven't got the gamma up from 1.9 to 2.2 where it should be, certainly not in games where only the OSD settings are applied. So it could be a symptom of that.
As for the general color impression, I would say that after just the TFTcentral calibration, it looked really accurate for photo/video - none of that oversaturation that seems to persecute all of the flatscreen panels. All of a sudden, plants and trees looked very realistic indeed, instead of sort of plasticky greenery.
Calibrate game graphics: The only question that remains for me is how to make calibration settings beyond what's available in a monitor's OSD menu apply to games. I guess you'd calibrate Windows first and make that check out, and after that you'd not change the OSD settings but just (as I said) guess the Gamma and any other settings the panel offers by looking at the game, since the lagom tests (AFAIK) do not use DX at all (nor should they!).
So I guess a vendor-specific calibration program for DX and OGL is needed to make sure you have it right for games. Or some game or gfx card stress test demo might have it built in.