Modern Mayincatec Empire

A common feature of alternate histories where the point-of-divergence is far enough back is that a Mayincatec civilization has somehow survived to the present day, and now rules a large chunk of the Americas.

Like Zeppelins From Another World, generally done as a throwaway "Look how different this world is" detail, without any serious or detailed consideration of how it happened or what the geopolitical effects were. (Possibly correlated with alternate worlds where the technology level never got high enough for zeppelins.)

Incidentally, in Real Life, there are pockets of Mayans, Aztecs and Incans who still practice their old traditions - while the ruling class were deposed, not all of the peasants were completely assimilated.

Comic Books

 * One story in Tom Strong has an expansionist interdimensional "Aztech" Empire. When the Spaniards first arrived at their shores, they were waiting with machine guns.

Literature

 * Charmed Life by Diana Wynne Jones - mentioned during the history lesson
 * The Lord Darcy series by Randall Garrett features one of sorts, though it's subject to the Angevin (Anglo-French) empire, but still retains some independence.
 * Quest Crosstime by Andre Norton. The Crossroads of Time, to which Quest Crosstime is a sequel, also briefly mentioned a hybrid Celtic-Germanic-Mayincatec civilization.
 * The Mask of the Sun by Fred Saberhagen
 * In A Midsummer Tempest by Poul Anderson, a crosstime traveller mentions having recently visited a world like this.
 * One of the virtual reality settings in Otherland is a modern Inca empire.
 * In The Case of the Toxic Spell Dump by Harry Turtledove, Spain didn't colonize America until considerably later than in our world. So there's an Aztec empire (with a thin veneer of Spanishness) in the place of Mexico, and all the Spanish names in the southwestern United States are in English (the protagonist lives in Angels City; the spell dump of the title is in St. Ferdinand's Valley; and so on...)
 * Cat-A-Lyst by Alan Dean Foster.
 * While not "modern" (Napoleonic wars) Temeraire has the South American empires fending off conquistadors with their firebreathing dragons and surviving.
 * In Pastwatch the Redemption of Christopher Columbus, by Orson Scott Card, the Tlaxcala apparently took over the world in a previous iteration of the world's history. The people of that timeline
 * According to the book, this is due to them being more willing to adopt European technology and warfare than their Aztec enemies (whom they have wiped out by the time they first encountered Europeans).
 * This is only part of the reason. The other reason is Columbus leading another Crusade, resulting in Europe being in no shape to resist an invasion from overseas.
 * And in the end,.
 * One of the parallel worlds described in Vasili Golovachov's novel The Envoy features a Modern Mayincatec Empire that has taken over most of the world. They have been unable to conquer Africa due to Africans banding together in a similar manner to resist foreign occupation. It is notable that martial arts are virtually unknown in this world. A high-caste group of warrior telepaths have developed their own system of hand-to-hand combat, relying on their telepathy to allow them to gain the upper hand.
 * This is, possibly, a nod to Orson Scott Card's Pastwatch.
 * In The Time Of The Sixth Sun series by Thomas Harlan: Japanese exiles fleeing a successful Mongol invasion of the islands, settle in America and introduce horses and steel to the New World, leading eventually to the dominance of the Nippon-Méxica empire. In Space.
 * "The Bison Riders" by Brad Linaweaver depicts an alternate history where the Aztecs survived and started fighting the North American plains Indians. It was first published in Tales From the Great Turtle, a collection of short stories with a native theme (compiled by Piers Anthony).
 * In Aztec Century by C. D. Evans, Cortez, instead of conquring the Aztecs, married an Aztec woman, and switched sides, giving the Aztecs advanced technology that, now, mean they are a world superpower, conquring much of the world.

Tabletop Games

 * GURPS. In Alternate Earths, one of the alternate realities was Ezcalli, a world dominated by the Tenocha Empire (a heavy updating of the Aztec Empire, set in 1840). In Alternate Earths II, the 15th century Midgard setting included human-sacrificing Mixtecs.
 * The main setting of the otherwise pretty much forgotten tabletop game "Mecha" was one where a Mayincatec civilization obliterated the Conquistadors - because they were given giant robots by aliens to act as their 'champions'.

Video Games

 * In Rise of Nations the Mayans, Aztecs, and Incas get special versions of modern units.
 * Some Civilization games let you become one of these yourself. When the AI is playing one of the native American civilizations, results are more mixed: the Inca and Maya tend to last and even do well, but the Aztecs tend to be too aggressive for their own good, and whichever North Americans they've decided to include tend to just get rolled over early on or decline into increasing irrelevance. It gets weirder when you see Montezuma in the modern days, wearing a suit and tie, claiming he'll sacrifice warriors to the friendship of the nation he's talking to. Not much weirder than Ieyasu ordering his people to commit Seppuku when they invade your territory by accident, the backdrop of it being a very cosmopolitan Tokyo, granted.
 * The tutorial campaign of Empire Earth 2 follows the Aztec Empire through an alternate history where it wins against the conquistadors, establishes an independent nation, helps the Americans defeat the British, and ends up fighting a war with a fascist Inca Empire in the 1930s.
 * In the obscure RTS game Theocracy, the player leads and manages a fictional meso-american empire as it goes to war against other such tribal nations and towards the end, the invading Spanish. If the player beats the game, the ending cinematic shows that the player's empire has survived Twenty Minutes Into the Future, and observes a bustling modern city (bordering on Cyberpunk) with architecture and clothing styles clearly based on ancient meso-american culture but full of skyscrapers, high-tech cars, and holograms.
 * from Sonic Chronicles.
 * Possible though very difficult to accomplish due to vastly inferior starting tech family and tribal government in Europa Universalis III.

Web Original

 * Ilivais X opens with this, with the result being a massive Lensman Arms Race in which the Spanish and Aztecs conquer their entire hemispheres, create space colonies in the 1700s, and start fighting in Humongous Mecha a few decades after our time. The Aztecs are portrayed as being fairly quirky for an empire, while the Iberians only have a few named characters and have a generally cold and bland feel.
 * There is a timeline in the Althistory wiki called simply as Aztec Empire, in which the Aztecs defeat Cortez and fearing another invasion, modernized and survived through the present day. The Incas do the same and is the rival empire of the Aztecs.