EDIT: Left the below for historical purposes, but the 2K Launcher has been completely removed, so I would now recommend the game again.

OLD: Previously I would have recommended this game wholeheatedly, as you can tell from my wild playtime, but the 2K Launcher has developed a very nasty bug that causes it to think you don't actually own the game. For other Firaxis games like Midnight Suns or XCOM2 this isn't a problem because you can either bypass the terrible launcher (Midnight Suns) or there are community-made alternatives (XCOM2), but the game binary for Civ6 has been lobotomized so that it now checks for LauncherPatcher.exe, which in turn searches for and runs the 2K Launcher, only allowing the game to launch if the Civ6 executable is launched via the 2K Launcher itself. This means that previous methods of bypassing the 2K Launcher, such as directly launching the game executable, using a launch option in Steam properties, or using the old LaunchPad launcher no longer work.
This also means that if, for example, 2K stops supporting the game, you will no longer be able to play the game as their launcher will not validate your ownership of the game; it also means that you cannot play Civ 6 offline at all. This is actually a particular kind of civil crime known as 'defrauding', which is waived by the EULA basically saying that "you agree that you don't actually own the software you purchased and we can revoke your ability to use the software at any time", but EULAs are rarely tested in court because individuals don't have the power to test large corporations and class action suits for games are fairly uncommon.

The game itself is great, though.

EDIT: Left the below for historical purposes, but the 2K Launcher has been completely removed, so I would now recommend the game again. OLD: Previously I would have recommended this game wholeheatedly, as you can tell from my wild playtime, but the 2K Launcher has developed a very nasty bug that causes it to think you don't actually own the game. For other Firaxis games like Midnight Suns or XCOM2 this isn't a problem because you can either bypass the terrible launcher (Midnight Suns) or there are community-made alternatives (XCOM2), but the game binary for Civ6 has been lobotomized so that it now checks for LauncherPatcher.exe, which in turn searches for and runs the 2K Launcher, only allowing the game to launch if the Civ6 executable is launched via the 2K Launcher itself. This means that previous methods of bypassing the 2K Launcher, such as directly launching the game executable, using a launch option in Steam properties, or using the old LaunchPad launcher no longer work. This also means that if, for example, 2K stops supporting the game, you will no longer be able to play the game as their launcher will not validate your ownership of the game; it also means that you cannot play Civ 6 offline at all. This is actually a particular kind of civil crime known as 'defrauding', which is waived by the EULA basically saying that "you agree that you don't actually own the software you purchased and we can revoke your ability to use the software at any time", but EULAs are rarely tested in court because individuals don't have the power to test large corporations and class action suits for games are fairly uncommon. The game itself is great, though.