If you haven't played Civilization in a while, heads up: things are changing. A lot.
PC Gamer today posted gameplay of the first 100 turns, and there are an insane amount of changes if you're returning from Civilization 4 or 5. The tech tree has been broken up into two segments: technology and civics. There's more of a push for your surroundings to play an influence in your build order, which is a nice idea.
The introduction of policies is interesting as well. It's all contained in the video below, so check it out.
I'm intrigued to see whether there will be much of a need to adjust your policies a great deal. I can't see why most people wouldn't want to have builders and farmers early on, switching when you need to lower the cost of your army upkeep later on.
The update to movement seems enormous as well. That could be a thing that really pisses people off, especially in multiplayer, since they won't be able to recon their surroundings in the early stages as quickly.
Making something longer for the sake of doing so is almost guaranteed to be divisive, but we'll see how it plays out on October 21 when Civ 6 launches for PC, Mac, Linux and SteamOS.