Civ 6 is a bit like golf. You might be playing against different opponents with different skillsets, but you are always playing against the course. In Civ 6, you are always playing against a new "course," at least if you are playing the popular Continents map. The different terrain and resource placement means you have to adapt your playstyle every game.
All of which encourages replayability. Civ 6 is the game I always come back to.
I play different kinds of games: Guild Wars 2, Fallout 4, Stranded Alien Dawn, Skyrim, Railway Empire 2, Witcher, Medieval Dynasty. If I like a game, I think nothing of sinking hundreds, sometimes thousands of hours into it. But once I've wrung everything I can from a game, gotten all the achievements, played all the scenarios, I tend to walk away and never look back.
But Civ 6 is different.
After I have exhausted a given game and as I search for the next big time suck, I boot up Civ 6 yet again, pick a civilization I haven't played yet and lose myself, yet again, in tech trees, city design, and yes, world conquest. A campaign can take from four to ten days, depending on how much the rest of my life interferes. It is a glorious time, immersed in nuance, strategy and the occasional gnashing of teeth.
A reluctant shoutout is due here to the Mayhem mode that was introduced in the Brave New World expansion to Civ 5 and operates in the background of all Civ 6. I am proceeding nicely in the early game with Tokugawa, a civilization that fully blossoms in the late game, when Menelik decides to attack me for some imagined slight. I had thought we were getting along, trading, respecting each other's borders. Silly me. Time for new strategy. Thank you Mayhem. The game does not let you get too comfortable.
A feature of the game that is often overlooked but deserves a high five all its own is the history accompanying each civilization, district, and Great Person. You can, of course, choose to skip each mini-lesson, but take it from somebody who reads EULAs and the sides of cereal boxes, there's a lot of fascinating stuff that somebody went to a lot of effort to include.
Finally, some cautions. I have already alluded to the immersiveness and I am hardly the first to note that grocery shopping or lawn mowing can take a back seat while playing Civ 6. On balance, that's a good thing. It is what I celebrate in a great game. But it is easy to forget to take a walk or reserve time for family and friends. And, of course, the primary reason for such interludes is to encourage a mental reset, perhaps inspiring a shift in strategy or even just a question as to how something you might have ignored up to that point might help. You can think of such interludes as playing the game, if you will, just at a lower intensity.
Also, if you are an achievement completionist, give up all hope ye who enter here. There are an astonishing 320 possible achievements. I have 41 of them after 500 hours on the PC. I probably played about that much time on the PlayStation, before I switched to the PC and the comfy chair and big screen in the living room, but those PS achievements are gone forever. Still, completing all the achievements in this game is for the truly obsessed. Consider therapy.
Inexplicably, Civ 6 does not take advantage of Steam cloud saves. Don't be like me and open up your laptop in a hotel one night only to discover that all my saved games are playable solely from my home computer.
Finally, the negative reviews tend to fall into two camps. Either the game is unplayable because of glitches or Civ 5 was better. I can't remember any crashes on the PC, but in any event set your Autosaves to ten and you will be covered. As for the Civ 5 devotees, I'm happy for you that you found a game you love. But it's also true that change can be hard, for some people more than others. Civ 6 is a wonderful game regardless of how wonderful Civ 5 was.
If you have any interest in strategy 4x games, it is hard to imagine that you have not discovered Civ 6 yet, but by all means I encourage you to do so. And even if you have discovered it, but have been away for awhile, Civ 6 is exceptional in welcoming you back (and you can discover anew that a fighter jet cannot take out a missile cruiser). It's a fun ride either way.