Diablo series

Diablo is a dark fantasy-themed action role-playing game developed by Blizzard North and released by Blizzard Entertainment in December 1996.

Set in the fictional Kingdom of Khanduras (located in the Diablo series fantasy world of Sanctuary), Diablo has the player take control of a lone hero as he or she battles to rid the world of the eponymous Lord of Terror. Beneath the town of Tristram, the player journeys through sixteen dungeon levels to ultimately come face to face with Diablo and his demon minions.

Diablo was a best-seller and an expansion pack, entitled Hellfire, was released in 1997, although it was not created by Blizzard. This was followed by a sequel, Diablo II, in 2000.

Official Diablo site @ Blizzard
Diablo @ Wikipedia
Diablo @ MobyGames
Diablo @ Gamespot
Diablo Gameplay Guide

Hellfire is the only authorized expansion pack for Diablo. It was released in 1997 and developed by Synergistic Software, a Sierra division.

Blizzard has never released a first-party expansion for Diablo.

Hellfire's storyline occurs as an aside to the main story arc of the original game. A sorcerer, while performing a ritual, unknowingly releases the demon Na-Krul unto the town of Tristram, but before it can completely escape, the sorcerer magically seals the doors. The player is later tasked with venturing into Na-Krul's lair and vanquishing it.

Hellfire @ Wikipedia
Hellfire @ MobyGames

In 1998, a PlayStation version of Diablo was published by Electronic Arts. The game lacked online play, but featured a two-player cooperative mode. It also featured an option to learn the story through a narrator without having to find the books in the game. This feature can be found on the main menu under the title 'history'. This version was infamous because of its need for 10 blocks free on a PlayStation memory card; the standard size of memory cards for the platform was 15 blocks.

Due to translation to the Playstation platform, the controls can be difficult, especially with ranged weapons, and the two-player mode throws both characters on the same screen, often making it problematic to negotiate the various rooms of any given level.

Diablo for PS @ Gamespot

Diablo II stayed true to the dark fantasy-theme of the original as well as its addictive hack'n'slash gameplay. It was release in June 2000 by Blizzard North, and by April 2001, was one of the most popular PC games, even earning a spot in the 2000 Edition of Guiness as being the fastest selling computer game, with 1 million sales in the first 2 weeks.

Besides numerous gameplay and graphical enhancements, Diablo II introduced an improved version of Battle.net that helped stop cheating so common in the original Diablo.

The story of Diablo II takes place soon after the end of the original Diablo, when the Lord of Terror was defeated by a hero. After this event, the hero is corrupted and gradually loses control of Diablo's soul. In the opening cinematic of Diablo II, we witnesse the fallen hero (known as the Dark Wanderer) totally lose control, unleashing the demons of Hell upon a tavern. The new player character is a different hero following in the wake of the destruction, chasing the Dark Wanderer, hoping to put an end to the demon lord within him.

Official Diablo II site @ Blizzard
Diablo II @ Wikipedia
Diablo II @ MobyGames
Diablo II @ Gamespot

Released in June 2001, Lord of Destruction is an official expansion for Diablo II, and unlike Hellfire, this expansion was developed directly by Blizzard North. This expansion not only added new character classes and scenarios, but also improved gameplay in both solo and multiplayer modes. Game resolution was also increased from 640x480 to 800x600.

The story continues where Diablo II ended. Two of the three Prime Evils, Mephisto and Diablo, have been defeated and their Soulstones have been destroyed, preventing their return. However, the last Soulstone was taken by Baal, the third brother and the very last remaining Prime Evil - the Lord of Destruction, who is seeking the Worldstone. It is the source of all the Soulstones and their powers. Baal wishes to obtain it, corrupt it and complete his brothers' plan to conquer the mortal realm and use it as a staging area to besiege the Heavens.

Official Lord of Destruction site @ Blizzard
Lord of Destruction @ Wikipedia
Lord of Destruction @ Gamespot

A Diablo collection was released in September 2001 which included Diablo, Diablo II, and Lord of Destruction (Hellfire wasn't developed by Blizzard North and wasn't part of the main Diablo storyline so it is ommited from this release).

The game takes place in Sanctuary, the dark fantasy world of the Diablo series. This world was saved twenty years prior by a handful of unnamed heroes in Diablo II. Warriors that survived the onslaught of the armies of the Burning Hells have gone mad from their ordeals, and it is up to a new generation of heroes to face the forces of evil threatening the world of Sanctuary. Players will have the opportunity to explore familiar settings such as Tristram.

Diablo III information @ Wikipedia