Assassin’s Creed Syndicate runs at 1440x1620 upscaled to 4K, with a native 4K minimap. It holds 30FPS well.

Assassin's Creed: The Ezio Collection features "4K dynamic rendering support" – in other words, it is upscaled to 4K from an undisclosed resolution.

Battleborn gives players two options: 1080p at 60fps, or native 4K at 30fps.

Battlefield 1's campaign gets a decent image quality boost thanks to higher quality textures and particle effects. On a 4K screen, it runs at dynamic resolutions from 1080p all the way up to 1656p. On an HD TV, the downsampled images look really nice. Frame rates are also improved. On the multiplayer side of things, the PS4 Pro's frame rate sits 10-15fps above that of the vanilla PS4.

Battlezone runs at a higher resolution (that is then downsampled for VR), and features improved dynamic lighting in the Cobra cockpit, and increased reflective lighting resolution.

Bound runs at a native 4K resolution at 60fps.

Call of Duty: Black Ops 3 supports "enhanced dynamic 4K gaming" (whatever that is) in multiplayer.

Call of Duty: Infinite Warfare runs at 2880x1620 on PS4 Pro. Its framerate is much more consistent on PS4 Pro. Those with HD TVs benefit from downsampling.

Call of Duty: Modern Warfare Remastered features improved textures and a dynamic resolution that upscales to 4K.

Deus Ex: Mankind Divided uses checkerboard rendering (upscaling) on PS4 Pro to switch between two resolutions: 3840x2160 and 3200x1800. Interestingly, the framerate hitches more often on PS4 Pro than PS4, but it's a barely detectable minor annoyance at most.

Darksiders Warmastered Edition runs at native 4K at 60fps on Pro.

Dishonored 2 runs at 1440p on PS4 Pro, and the frame rate is steadier (but not a perfect 30 fps).

Driveclub VR has apparently been patched, but I can't tell what has been done, and info is lacking.

Farming Simulator 17 has three modes for PS4 Pro owners: native 4K, 1080p at 60fps with an improved draw distance, or 1440p at 60fps. It features higher quality shadows displayed at an increased draw distance across all three modes.

Final Fantasy XV has two Pro modes: 1080p @ 60fps, or non-native 4k @ 30fps with enhancements to visuals and shadows.

FIFA 17 runs in native 4K @ 60 fps on Pro.

Firewatch runs at 1440p on the Pro with a 4K UI and enhanced detail. PS4 Pro owners with 1080p display get enhanced detail distance, smoother loads, and much higher quality shadows.

forma.8 runs in native 4K @ 60fps with multisample anti-aliasing.

Futuridium EP Deluxe runs in native 4K @ 60 fps.

Helldivers runs at a higher than 1080p yet undisclosed resolution. It supports HDR.

Hitman runs at a resolution of 2560x1440p on Pro, with significantly faster loading times and texture streaming, improved texture filtering, and a rock solid frame rate of 30fps. There are better lighting and reflective surface effects, and aliasing is reduced. Those without a 4K TV get higher quality shading and less flickering highlights.

Hustle Kings runs in native 4K on PS4 Pro.

Infamous: Second Son / First Light runs at an increased resolution on Pro, runs at a higher framerate than it does in vanilla PS4, and supports HDR as well.

Killing Floor 2 runs at a resolution of 1800p that is then upscaled to 4K. "The extra resolution increases overall environment, weapon, and character detail beyond what is perceivable on a 1080p display," says Tripwire. It also features higher quality textures, increased dynamic shadow resolution, and an increased framerate whether you are playing on an HD or 4K screen.

Knack runs at a higher than 1080p yet undisclosed resolution.

Mantis Burn Racing runs at native 4K @ 60fps, or native 4K @ 30fps for 4 player split-screen on PS4 Pro.

Middle-earth: Shadow of Mordor runs at a higher resolution on Pro.

NBA 2K17 runs at a native 4K resolution at 60 fps with HDR support. On a 1080p display, this results in "much better anti-aliasing" with HDR support according to 2K.

Paragon on Pro features enhanced visual effects, procedural ground cover, higher scene complexity, greater texture fidelity, and dynamic reflections.

Ratchet & Clank runs at a higher resolution and supports HDR. On a 1080p display Pro allows for a "big increase in gameplay image quality" according to Insomniac.

Resogun will soon support 4K and HDR. "Imagine all of the voxels, particle effects and the fast-paced action even in greater, more eye-candy indulged experience. No actual date to announce yet, but it should be coming soon enough," says Housemarque.

Rez Infinite runs at a native 4K on Pro, and the VR version is rendered at a
1920x1080 resolution for each eye as opposed to the standard PS4's output of 1440x810. "Even though the final resolution displayed on the headset is the same either way, the extra rendering from the PS4 Pro makes a difference: each particle looks a little more clear, a little more solid, adding up to objects and enemies that look more distinct and 'real', whether close-up or at a distance," says Enhance Games.

Rigs Mechanized Combat League runs at an undisclosed higher resolution.

Rise of the Tomb Raider has three modes: (Upscaled) 4K Resolution mode @ 30fps, High Frame Rate mode @ 60fps, and Enriched Visuals mode which is 1080p @ 30fps but improves overall image quality via hardware tessellation, anisotropic filtering, additional dynamic foliage, and more.

Robinson: The Journey runs at a higher resolution.

Skyrim: Special Edition runs at native 4K on Pro.

Smite runs in 4K @ 60fps.

The Elder Scrolls Online runs at a native 4K resolution on Pro, or in a 1080p Enhanced Mode that adds graphical enhancements like ambient occlusion and water reflections, as well as improved shadow fidelity.

Thumper runs in native 4K @ 60fps. On PS VR, it features improved rendering quality at the same 90 FPS as the regular PS4.

The Last Guardian upscales to 4K, makes minor fixes to framerate, and supports HDR.

The Last of Us Remastered/Left Behind allows you to choose whether you want to play in the game’s original target framerate of 30 frames per second at 2160p (4K) or at a high targeted 60 frames per second at 1800p on a 4K display. It also supports HDR and 4K photo mode, and you can use the Share button on PS4 Pro to stream at up to 1080p at 60 frames per second, or capture in-game highlights at 1080p at 30 frames per second.

Titanfall 2 runs at a higher resolution and sticks closer to its 60fps target.

Viking Squad runs in native 4K at 60fps.

The Witness has two modes on Pro: 1440p resolution upscaled to 4K @ 60fps with text and UI rendered at native 4K, or native 4K resolution 30fps. Those with a 1080p display get a resolution bump from 900p to 1080p @ 60fps and increased antialiasing quality.

Uncharted 4's campaign runs at a resolution of 1440p, while its multiplayer resolution has been increased from 900p to 1080p. It supports HDR and 4K photo mode.

Watch Dogs 2 runs at 1800p with superior image quality than on the vanilla PS4.

Wheels of Aurelia runs in native 4K @ 60 fps.

World of Tanks runs at a resolution of 3200x1800, and the PS4 Pro does a high quality upscale from that to 4K (3840×2160). It also features higher quality anti-aliasing and smoother framerates on Pro. HDR is supported.

Note: Super Stardust Ultra, Neon Chrome, PlayStation VR Worlds, Ride 2, The Playroom VR, Wheels of Aurelia, and XCOM 2 are supposedly all patched for PS4 Pro, but I can't find exactly what these patches do – if indeed they exist at all!