Conclusion
As a seasoned Civilization player, Civilization VI will instantly make you feel at home, even with some new or changed concepts. The game has a tutorial for returning Civilization players as well as a separate tutorial for newbies to the series. While the graphics are a bit more cartoonish, they look fantastic, especially thanks to little details in animations and models.
Graphics options are plentiful and should let you optimize the game's performance to work well on your graphics card's hardware. What did come as a surprise to me was the lack of DirectX 12, a feature that especially AMD has used for their marketing for a long time. Since the same has happened to other titles, I suspect that developers underestimated the challenges posed by DirectX 12, which offloads many important tasks from DirectX to the game engine itself, adding extra complexity for developers and possible new concepts that aren't so easy to master.
Performance on NVIDIA cards is very good. You can basically run the game at 60 FPS on Ultra. The typical recommended resolution for each card is 1920x1080 for a GTX 1060, 2560x1440 for a GTX 1070, and 4K for a GTX 1080.
Even though the game requires 3-4 GB VRAM in Ultra (which isn't a lot), we see decent, stable framerates from cards with smaller amounts of memory, framerates that fall in line with their expected shading performance. This is definitely good news for people who - for economical reasons - bought cards with smaller memory amounts, like the GTX 1060 3 GB or RX 480 4 GB.
AMD cards seriously lag behind in performance, with the RX 480 unable to reach 60 FPS at even 1080p. Overall, the performance difference to NVIDIA is similar to what we've seen in many other, older DX10/11 games. Recent DX12 titles have usually improved performance for AMD cards, and I hope it will be the same for Civilization VI once DirectX 12 support is released. Unfortunately, there is no indication yet of when that will happen. Still, even as a Civilization veteran using AMD graphics, I'd buy the game now. It's just fine at lower settings, and once you've mastered the gameplay changes, you will quickly reach a state of "just one more turn", which will usually lasts for most of the night.