There are 5 historically based campaigns, which conscript the player to specialized and story-backed conditions, and 3 additional single-player game modes; multiplayer is also supported.

The design team focused on resolving significant issues in Age of Empires, but noted on release that some problems remained.

The HD Edition includes the original game and the expansion The Conquerors, as well as new campaigns, civilizations, and updated graphics for high-resolution displays.

Age of Empires II is a real-time strategy game that focuses on building towns, gathering resources, and creating armies to defeat opponents.

Villagers require checkpoints, typically depository buildings (town center, mining camp, mill, and lumber yard), in order to store gathered resources.

There are 5 campaigns in The Age of Kings, containing historically based scenarios such as Genghis Khan's invasion of Eurasia, Barbarossa's Crusade, and Saladin's defence of the Holy Land.

[14] The population capacity, which can be capped at anywhere between 25[17] and 200 in intervals of 25,[18] is based on the number of houses, Castles, or Town Centers—the main building in a player's town—which have been built.

The Age of Kings introduced two significant new features for unit management: the idle villager button, which helps players identify villagers that have not been assigned a task, and the town bell, which sends all of the player's villagers into their Town Center, Castle, or tower for safety;[19] units garrisoned within these 3 buildings, especially archers, increase the building's firepower (towers fire more arrows with units garrisoned inside), including the Town Center, which cannot fire anything at all without someone garrisoned there.

[25] To add variety, each civilization has a set of sound bites in its native language that are uttered by units when selected or instructed to perform a task.

[27] The most important economic building is the Town Center, where villagers are created, all types of resources can be stored, some technologies are researched, and the player can advance to the next Age.

[36] Since April 2013,[37] Steam supports in-game multiplayer for HD resolution[38][39][40] Prior to the completion of Age of Empires, Ensemble Studios had signed a contract with Microsoft for a sequel.

[44] The original Age of Empires was criticized for its artificial intelligence (AI), which did not "cheat" by attributing itself extra resources or using other techniques the human player could not, making it easier to defeat than in many other real-time strategy games.

[56] The game's sales in the United States alone totaled 469,376 by the end of 1999,[57] which drew revenues of $20.2 million, the second-highest domestic gross that year behind SimCity 3000.

[60] Age of Empires II's domestic success continued in 2001: with sales of 478,557 units ($19.4 million),[61] it claimed tenth place for the year.

[62] In the German market, Age of Empires II debuted in first place on Media Control's sales charts during October 1999, and by March 2000 had spent 17 weeks in the rankings.

[63] It received the Verband der Unterhaltungssoftware Deutschland's (VUD) "Platinum" award within one month of release,[64] indicating sales of 200,000 units across Germany, Switzerland, and Austria.

[65] By the end of February 2000, it had reached "Double-Platinum" status (400,000 sales) and become the German market's "most successful PC game of the past 12 months", according to the VUD.

[63] The game later received a "Platinum" sales award from the Entertainment and Leisure Software Publishers Association (ELSPA)[66] for at least 300,000 copies sold in the United Kingdom.

[19] GameSpy's Carlos Salgado was appreciative of other features; he praised the ability to create individual profiles for different players and to customize hotkeys.

"[75] AllGame's Michael L. House enjoyed the use of sound bites in civilizations' native languages, which he said was "very influential in developing an era-enhancing atmosphere".

[26] Game Revolution's review explained that by being set in a more recent epoch of human history, The Age of Kings was able to "add character to an otherwise impersonal style of gameplay".

[74] GameSpot said that with the screen full of units, "you can begin to imagine how their historical equivalents once prospered",[23] while GameSpy said The Age of Kings presents "realism rarely seen in the RTS genre".

[73] IGN staff argued that while the strengths and weaknesses attributed to different civilizations made the game more realistic, the fact that they were still mostly the same prevented The Age of Kings from "delivering the same battlefield impact of StarCraft or Tiberian Sun".

[75] IGN's main criticism was directed at the in-game speech used in campaigns; it rhetorically asked "why can't they just find a Frenchman to do a French accent?

"[75] Alex Constantides of Computer and Video Games rated the graphics highly, saying that some in-game buildings are "so grand you'll even feel guilty about burning them to the ground".

[87] Empire Earth's design was also similar to that of The Age of Kings; GameSpot said it "borrows most of that game's controls, interface features, and even some of its keyboard shortcuts".

[99] In 2012, Hidden Path Entertainment began working on a high-definition remake of Age of Empires II, an effort spearheaded by Matt Pritchard, an original lead programmer at Ensemble Studios.

It includes new maps, campaigns (Alaric I, Bari, Dracula, El Dorado, Francesco I Sforza, and Prithviraj), units, a new game mode, an increase of the maximum population limit from 200 to 500,[103] and numerous balance and gameplay adjustments.

[106] A second expansion pack for Age of Empires II HD, The African Kingdoms, was released on November 5, 2015, and introduces four new civilizations: the Berbers, Ethiopians, Malians, and the Portuguese.

[110] It is set in Southeast Asia, and adds four civilizations (Burmese, Khmer, Malay, and Vietnamese), each with its own fully voice-acted campaign (Bayinnaung, Suryavarman I, Gajah Mada, and Lê Lợi, respectively), as well as a new map type with environments, units such as the ballista elephant, improved AI, and more.