Can you tell me (honest question) what improves with 4k for games? I mean, for regular stuff you can see more details on the picture, but games usually just render essentially same picture only for larger resolution. And picture with fullhd and modern capabilities is also already pretty smooth, so does 4k bring anything (I guess it can add a bit of smoothness as additional step of AA)? Is it worth the trouble?
At the current price I don't think it's really worth it, no. Really few games manage to take full advantage of 4K (Doom '16, as I mentioned, is one of them). Too many console ports with low texture resolutions and terrible optimizations these days. Older games will of course fare much better but the additional sharpness in the graphics is probably not worth the price of the hardware. For gaming I think 1440p and a high framerate are a better compromise at the moment.
That being said I have some trouble going back to my 1200p screens at work after being used to 4k at home. Surprisingly even for emacs and other work-related things 4K makes a pretty huge difference in my experience. Everything remains razor sharp even with a small font. I can split my screen and display a few full page datasheets and schematics alongside my code. No need to zoom in or anything. No aliasing, no pixels, I find it very relaxing.
Those hold up pretty well at 4K. In contrast I present to you Wolfenstein: The New Order which often looks very mediocre and yet manages to run worse than DOOM:
Everything has More Detail, sometimes more than you care about. In some ways this feels like it's Not Important, except you definitely notice it, especially if your game has sliders that determine how far away they start doing detail culling by using lower-resolution models/textures. I can safely turn off anti-aliasing everywhere, which basically seems to balance that there are 4x as many pixels. ;)
World of Warcraft: Everything looks the same, except text is prettier, item textures are more detailed, and spell icons suddenly have noticeable details. ("Hey that's a guy with a shield! I never noticed that!")
Dishonored, or other FPS-es: Far-away details suddenly are not lost in the haze of antialiasing. Wires and greebling on bridges are visible, and Look Good. HUDs and ammo displays seem to universally SUCK -- they are often not scaled in older games.
All the face textures in most older games end up supporting the higher detail textures, but it gets closer to the uncanny valley. (I notice this a lot in bioshock infinite.) I haven't re-played Wolfenstein.
It's much like looking at the same picture or webpage on a retina screen vs a non-retina screen. Text looks better, some other things look much the same. Anything vector-based (HUDs, etc) might look better.
For 3D the biggest improvement is you have more pixels to render objects at long distance, which is huge for games with large camera viewing distance. For example, you can spot enemy much easier in Battlefield.
I see your point. I guess it also requires much larger screen. Because if 1 pixel man will be moving on my 27-inch fullhd screen, even though on 4k display it will be 4 pixels, it still be same physical size and not much easier to notice :)
