Victories
Victories in Civilization VI are similar, yet slightly different than those in Civilization V. In Civ VI, the Diplomatic Victory has been replaced with the Religious Victory and multiplayer modes have a different set of victory conditions. Domination has been changed from a sort of "conqueror" mentality to that of a "survivor" one. Science Victories are the same in principle as they were in Civ V, but differ in some specifics. Lastly, Cultural Victories are also strikingly similar to those found in Civ V, but, like the Science Victory, the specifics are different.
Domination
A Domination Victory is easily the most straight-forward victory condition. To earn this victory, one must be the last player in possession of of their original capital. In other words, you do not need to conquer any other civilizations' capitals to win in this category (contrary to popular belief); you simply need to hold onto yours while everyone else loses theirs. Usually this entails one player conquering all the other capitals in the game, but this is not actually how one achieves this victory. Essentially, you must be the last "survivor," not necessarily the conqueror.
If you end up losing your original capital but not your other cities, you can still win in every other victory condition. However, unless you recapture your capital, you are disqualified from a Domination Victory.
Score
Score Victories are won by the civilization that has the highest score at the end of a game and no one has won by any other means. By default, the game ends in the year 2050, but this can be changed in the Advanced Setup when starting a new game. This is by far the least likely victory one will naturally encounter.
In order ot build up score, players must advance in nearly every facet of a standard game. The number of civics, number of population, number of cities, number of technologies, number of "future technologies," number of Wonders, number of military accomplishments, number of Great People, and number of of beliefs all contribute to one's score.
Science
The Science Victory is arguably the most time-consuming victory condition. In order to win in this category, players must ultimately launch the Mars Colony, which requires many of the last techologies on the tech tree. However, certain steps must be taken before the Mars colony can be launched.
- Research the Rocketry technology, build a Spaceport in one of your cities, and build/launch the Earth Satellite city project. This will alert all players in the game that the space race has begun and that someone is pursuing a Science Victory. It also reveals the entire map for the player who launched the satellite.
- Research the Satellites technology and build/launch the Moon Landing city project. This grants a one time boost to Culture equal to ten times the Science produced per turn.
- Research Robotics, Nuclear Fission, and Nanotechnology (in any order) and then build the Mars Reactor, Habitation, and and Hydroponics module city projects in any order. Each has to be built in a city with a Spaceport, so having multiple may be useful.
Once all these steps have been taken, the Mars Colony will be automatically launched and the game will end in a Science Victory on your behalf.
Religion
The Religious Victory requires that one religion become the predominant one in all the civilizations in the game. To do this players must make their religion dominant in at least 50% of all civilizations' cities, but not necessarily all of the cities. Players who do not found a religion (and there is a limit depending on the game's size) and those who have their relgion wiped out are ineligible to achieve this victory, but they can still make it difficult for others to achieve this victory.
Religion will passively spread through the passage of time to neighboring cities. However, players will need to use Faith to purchase Missionaries, Apostles, and Inquisitors to spread their religion and fight off the spread of others. Missionaries are useful for spreading religion, but cannot initiate theolgoical combat. Apostles are capable of spreading religion like Missionaries (and can do so more effectively), can initiate and perform more strongly in theological combat, and can even enhance a religion's beliefs. They are, however, more expensive than any other religious unit. Lastly Inquistitors are useful to maintaining your religion as the dominant religion in your empire, as they are incapable of spreading religion, but can initiate theological combat and eliminate the other religions currently present in one of your cities. Inquisitors are cheaper than Apostles, but an Apostle must first be purchased and spent to launch and inquisition, allowing one to then buy Inquisitors.
Wonders are also particularly useful in Religious Victories. Not only do many of them provide Faith, but many also provide unique benefits to those seeking to increase their religion's potency. For instance, Stonehenge provides the builder's civilzation with a free Great Prophet, which allows that civilization to found a religion early (likely earlier than any other civilization). Seeing as how a religious victory benefits from a great start better than nearly every other victory type, wonder construction can mean a lot.
Culture
Perhaps the most complicated victory is the Cultural Victory. Specifically, one must possess a a total number of visiting tourists that exceeds the domestic tourists of every other civilization. Essentially, this boils down to having as much Tourism and Culture as possible.
Tourism can be generated by a number of sources. Trade routes between civilizations, shared or conflicting late-game governments, open borders, Great Works (Writing, Art, or Music) stored in one's civilization, religious Relics stored in one's civilization, Holy Sites, National Parks, Artifacts stored in one's civilization, and Wonders all contribute to one's Tourism.