Much like in Diablo and Diablo II, the quality and attributes of equipment are randomized. In addition to base stats (such as damage and attack speed for weapon or armor points on armor), higher-quality items have additional properties, such as extra damage, attribute bonuses, bonuses to critical hit chance or sockets (which allow items to be upgraded and customized by adding gems for various stat bonuses). Magic-quality items have 1 to 3 random properties, rare-quality items have 4 to 6 random properties and legendary-quality items typically have 6 to 8 properties with varying degrees of randomness (for example, the Mempo of Twilight, a legendary helm, always has a socket, bonuses to elemental resistance, attack speed and life, a bonus to either Intelligence, Dexterity or Strength, and one additional random property, however the magnitude of these bonuses varies from item to item), and set items are a subtype of legendary items which provide additional, cumulative bonuses if multiple items from the same set are simultaneously equipped. Higher level monsters tend to drop higher level items, which tend to have higher base stats and bonuses.
The proprietary engine incorporates Blizzards custom in-house physics, and features destructible environments with an in-game damage effect. The developers sought to make the game run on a wide range of systems without requiring DirectX 10. Diablo III uses a custom 3D game engine in order to present an overhead view to the player, in a somewhat similar way to the isometric view used in previous games in the series. Enemies utilize the 3D environment as well, in ways such as crawling up the side of a wall from below into the combat area.
As in Diablo II, multiplayer games are possible using Blizzards Battle.net service, with many of the new features developed for StarCraft II also available in Diablo III. Players are also able to drop in and out of sessions of co-operative play with other players. Unlike its predecessor, Diablo III requires players to be connected to the internet constantly due to their DRM policy, even for single-player games.
An enhanced quest system, a random level generator, and a random encounter generator are used in order to ensure the game provides different experiences when replayed.
Unlike previous iterations, gold can be picked up merely by touching it, or coming within range, adjusted by gear, rather than having to manually pick it up. One of the new features intended to speed gameplay is that health orbs drop from enemies, replacing the need to have a potion bar, which itself is replaced by a skill bar that allows a player to assign quick bar buttons to skills and spells; previously, players could only assign two skills (one for each mouse button) and had to swap skills with the keyboard or mousewheel. Players can still assign specific attacks to mouse buttons.
Skill runes, another new feature, are skill modifiers that are unlocked as the player levels up. Unlike the socketable runes in Diablo II, skill runes are not items but instead provide options for enhancing skills, often completely changing the gameplay of each skill. For example, one skill rune for the Wizards meteor ability reduces its arcane power cost, while another turns the meteor to ice, causing cold damage rather than fire.
As in Diablo II, Diablo III gives players the choice to make hardcore characters. Players are required to first level up a regular character to level 10 before they have the option to create new Hardcore characters. Hardcore characters cannot be resurrected; instead they become permanently unplayable if they are killed. Hardcore characters are separately ranked, and they can only form teams with other hardcore characters. After dying, the ghost of a hardcore character can still chat, the name still shows up in rankings, but the character cannot return to the game.
Artisans are non-player characters (NPCs) who sell and craft. Two types of artisans can be introduced by completing a quest for each: Haedrig Eamon the Blacksmith and Covetous Shen the Jeweler. The Reaper of Souls expansion introduced the Mystic artisan, who can replace individual item enchantments and change the physical appearance of items. Artisans create items using materials the player can gather by scrapping acquired items and reducing them to their component parts. These materials are used to create items which will have random bonuses. Unlike Diablo II, rare and magic items can be enhanced, not just basic weaponry and armor. Crafting can also be used to train and improve the skills of the artisans rather than create new items. When artisans gain new levels, their shop reflects their higher skill level. The process of salvaging items into materials also makes inventory management easier. Blizzard stated that this crafting system was designed so that it would not slow down the pace of the game.
Followers are NPC allies that can accompany the player throughout the game world. There are three followers in Diablo III: Kormac the Templar, Lyndon the Scoundrel and Eirena the Enchantress, who each possess their own skills and background. As followers fight alongside the player, they gain new experience, skills, and equipment as they level up. Only one follower accompanies the player at a time, creating a gameplay strategy decision. Originally, followers were only going to appear in Normal mode; however, Jay Wilson stated at BlizzCon 2011 that followers would continue to be usable in later difficulty levels.
Followers do not appear in co-op games nor against Diablo, as he will trap them in a cage of metal bones.
On August 1, 2011, it was reported that Diablo III would feature two types of auction houses; one where players spend in-game gold and another where players could buy or sell virtual items for real-world money. The real-money auction house was not available in Hardcore mode.
Prior to release, Blizzard stated that nearly everything that drops on the ground, including gold, could be traded with other players either directly or through the auction house system. Aside from certain bound on account items, such as the Staff of Herding needed to access the Whimsyshire easter egg,
Blizzard stated there would be very few items that would be bound to a particular character and therefore un-tradable.
In order to get rated in South Korea, Blizzard had to remove the real-money auction house from the Korean release of the game as the auction house violated Korean anti-gambling laws.
In the gold-based auction house, a flat fee of 15 percent was taken from the final sale price of an auction. The real-money auction house fees were US$1, €1 or £1 (or equivalent) for equipment (weapons and armor) and 15 percent fee for commodity auctions, which included items like crafting materials, blacksmith and jewelcrafting plans, and gold exchange. There was an additional 15 percent "cashing-out" fee from proceeds gained selling items in the real-money auction house.
While the gold-based auction house was available to any player regardless of which region they play in, the real-money auction was restricted to players on their home region. If they used the global play function to play in a different region, they would not be able to access the real-money auction house. The real money auction house was opened on June 12, 2012 (June 15 in the Americas).
In March 2013, former Diablo III game director Jay Wilson stated that he felt the existence of the auction houses "really hurt" the game. "I think we would turn it off if we could," Wilson said during his talk. But the problem is "not as easy as that."
On September 17, 2013, Blizzard stated that both the gold and real-money auction houses would be shut down on March 18, 2014. On March 18, 2014, Blizzard closed all the auction houses in Diablo III. Players had until June 24, 2014 to claim gold and items from the completed tab on the auction house interface.
Player versus player combat (PvP) was added to Diablo III in a limited form with the 1.0.7 patch, in February 2013. The Brawling system provides a simple free for all area where between two and four characters can fight and defeat each other as long as they like, but without any scores or damage being tracked. Players can participate by choosing from their existing characters, with access to all of the gear and skill they have gathered from playing the game in single-player or cooperative mode.
PvP content for Diablo III had been discussed throughout the games development, but on March 9, 2012, Blizzard announced that PvP had been delayed and would not be included with the games release. Lead designer Jay Wilson said in a post on Battle.net that the PvP Arena system would arrive in a post-release patch; it would include multiple Arena maps with themed locations and layouts, PvP-centric achievements, and a quick and easy matchmaking system. "Well also be adding a personal progression system that will reward you for successfully bashing in the other teams skulls", Wilson added.
On December 27, 2012, Blizzard announced that the previously mentioned Team Deathmatch or Arena mode was cancelled, because it did not have enough depth. Instead a simple PvP system would be added for the time being. That PvP mode was initially named Dueling, and was renamed to Brawling before release. Although the PvP systems initially outlined were not released, Blizzard stated that they will add other full-featured PvP systems in a future free content patch. In a May 2013 interview, Diablo III developer Wyatt Cheng stated that the development team was looking to see how the Brawling PvP evolves, while they "continue to work on figuring out something more objective-based."
There are five available character classes from Diablo III and one from the Reaper of Souls