### Instruction: What is Age of Empires?
### Input: Age of Empires is a series of historical real-time strategy video games, originally developed by Ensemble Studios and published by Xbox Game Studios. The first game was Age of Empires, released in 1997. Nine total games within the series have been released so far as of October 28, 2021.

Age of Empires focused on events in Europe, Africa and Asia, spanning from the Stone Age to the Iron Age; the expansion game explored the formation and expansion of the Roman Empire. The sequel, Age of Empires II: The Age of Kings, was set in the Middle Ages, while its expansion focused partially on the Spanish conquest of the Aztec Empire. The subsequent three games of Age of Empires III explored the early modern period, when Europe was colonizing the Americas and several Asian nations were on the decline. Another installment, Age of Empires Online, takes a different approach as a free-to-play online game utilizing Games for Windows Live. A spin-off game, Age of Mythology, was set in the same period as the original Age of Empires, but focused on mythological elements of Greek, Egyptian, and Norse mythology. The fourth main installment in the series, Age of Empires IV, was released on October 28, 2021.

The Age of Empires series has been a commercial success, selling over 25 million copies. Critics have credited part of the success of the series to its historical theme and fair play; the artificial intelligence (AI) players have fewer advantages than in many of the series' competitors.
### Response: Age of Empires is a classic PC game originally developed by Microsoft, released in 1997. It has 4 versions now and is still being played online by many players.