Mike O'Brien is one of the three co-founders and current president of ArenaNet

ArenaNet

ArenaNet is a computer game developer and part of NCsoft Corporation, founded in 2000 by Mike O'Brien, Patrick Wyatt and Jeff Strain and located in Bellevue, Washington...

 and the leader of the Design and Content teams for Guild Wars

Guild Wars

Guild Wars is an episodic series of online 3D fantasy role-playing games developed by ArenaNet and published by NCsoft. Although often defined as an MMORPG the developers define it as a CORPG due to significant differences from the MMORPG genre. It provides two main modes of gameplay—a cooperative...

. Previously, he worked as a company director and a lead programmer at Blizzard Entertainment

Blizzard Entertainment

Blizzard Entertainment, Inc. is an American video game developer and publisher founded on February 8, 1991 under the name Silicon & Synapse by three graduates of UCLA, Michael Morhaime, Allen Adham and Frank Pearce and currently owned by French company Activision Blizzard...

 where he developed the 3D rendering

3D rendering

3D rendering is the 3D computer graphics process of automatically converting 3D wire frame models into 2D images with 3D photorealistic effects on a computer.-Rendering methods:...

 engine of Warcraft III: Reign of Chaos

Warcraft III: Reign of Chaos

Warcraft III: Reign of Chaos is a real time strategy computer game released by Blizzard Entertainment on July 3, 2002 . It is the second sequel to Warcraft: Orcs & Humans, and it is the third game set in the Warcraft Universe...

and led the development of Battle.net

Battle.net

Battle.net is a gaming service provided by Blizzard Entertainment. Battle.net was launched in November 30, 1996 with the release of Blizzard's action-RPG Diablo. Battle.net was the first online gaming service incorporated directly into the games that make use of it, in contrast to the external...

. He also worked on Warcraft II: Tides of Darkness

Warcraft II: Tides of Darkness

Warcraft II: Tides of Darkness is a fantasy-themed real-time strategy game published by Blizzard Entertainment and first released for DOS in 1995 and for Mac OS in 1996...

, Diablo

Diablo (video game)

Diablo is a dark fantasy-themed action role-playing game developed by Blizzard North and released by Blizzard Entertainment on December 31, 1996....

and StarCraft

StarCraft

StarCraft is a military science fiction real-time strategy video game developed by Blizzard Entertainment. The first game of the StarCraft series was released for Microsoft Windows on 31 March 1998. With more than 11 million copies sold worldwide as of February 2009, it is one of the best-selling...

, where he, among other things, designed and created the MPQ

MPQ

MPQ , is an archiving file format used in several of Blizzard Entertainment's games....

 archives used in all Blizzard games after Diablo. Mike O'Brien was featured as one of the most influential people in the computer and video game industry

Computer and video game industry

The video game industry is the economic sector involved with the development, marketing and sales of video games...

 on PC Gamer

PC Gamer

PC Gamer is a magazine founded in Britain in 1993 devoted to PC gaming and published monthly by Future Publishing. The magazine has several regional editions, with the UK and US editions becoming the best selling PC games magazines in their respective countries...

's September 1999 cover story "Game Gods".

Mr. O'Brien also previously developed an Apple II emulator for Windows, AppleWin

AppleWin

AppleWin is an open source software emulator for running Apple II programs in Microsoft Windows. AppleWin was originally written by Mike O'Brien in 1994 ; O'Brien himself announced an early version of the emulator in April 1995 just before the release of Windows 95...

, and old DOS ASCII game, Pyro 2

Pyro 2

Pyro 2 is an action/puzzle ASCII game where the player takes the role of a pyromaniac setting fires to the floors of several government buildings. The game is freeware and works on PCs running DOS through Windows XP.-Gameplay:...

.