Question: When was the lead developer for the game set within the Warhammer 40,000 universe born?

Context paragraphs:
Warhammer 40,000: Squad Command: Warhammer 40,000: Squad Command is a turn-based tactics game set in the Warhammer 40,000 universe, released on November 16, 2007, for the PlayStation Portable and Nintendo DS.  It was developed by RedLynx.  The game features three Space Marine Chapters pitted against three Legions of Chaos (two and two for the DS) battling it out on the planet of Ruhr III.  The game features units from the tabletop wargame.

Warhammer 40,000 Roleplay: Warhammer 40,000 Roleplay is a role-playing game system with multiple source books set within the "Warhammer 40,000" universe.  The first game using the system, Dark Heresy, was created by Black Industries, which closed soon after the initial release.  Official support was recently discontinued by Fantasy Flight Games.  The license has now been acquired by Ulisses Spiele.

Warhammer 40,000: Dark Nexus Arena: Warhammer 40,000: Dark Nexus Arena was a cancelled multiplayer online battle arena, twin-stick shooter video game developed and published by Canadian independent developer Whitebox Interactive, for Microsoft Windows.  The game takes place in the Warhammer 40,000 universe, created by Games Workshop.  The game combines traditional twin-stick shooting with four-versus-four team deathmatch mechanics.

Warhammer 40,000: Glory in Death: Warhammer 40,000: Glory in Death is a turn-based strategy video game for the N-Gage, produced by THQ.  It is based on the Warhammer 40,000 universe by Games Workshop.

Aeronautica Imperialis: Aeronautica Imperialis is a tabletop miniature wargame set within the "Warhammer 40,000" universe.  The game focuses on aerial combat between the different races of the Warhammer 40,000 universe.  Released in January 2007, it was developed and published by Forge World, a division of the British gaming company Games Workshop.

Warhammer 40,000: Storm of Vengeance: Warhammer 40,000: Storm of Vengeance is a real-time strategy video game developed and published by Eutechnyx.  It was released for Microsoft Windows, Android and iOS.  "Warhammer 40,000: Storm of Vengeance" was set in the "Warhammer 40,000" universe, it follows the Dark Angels, commanded by Grand Master Belial, and the Bad Moons, commanded by Ork Warlord Ghazghkull Thraka on the planet Piscina IV.  "Warhammer 40,000: Storm of Vengeance" was released on; 3 April 2014 (Steam), 23 April 2014 (Google Play) and 1 May 2014 (iOS).

Epic (game): Epic is a tabletop wargame set in the fictional "Warhammer 40,000" universe.  Whereas "Warhammer 40,000" involves small battles between forces of a few squads of troops and two or three vehicles, Epic features battles between armies consisting of dozens of tanks and hundreds of soldiers.  Due to the comparatively larger size of the battles, "Epic" miniatures are smaller than those in "Warhammer 40,000", with a typical human being represented with a high figure, as opposed to the 28mm minis used in "Warhammer 40,000".

Warhammer 40,000: Chaos Gate: Warhammer 40,000: Chaos Gate is a video game set in the gothic science fiction backdrop of the Games Workshop game system "Warhammer 40,000".  In it, players take command of a number of squads of Ultramarines under the leadership of Captain Kruger.  They are pitted against the armies of the Chaos Lord Zymran, who commands the traitor marines of the Word Bearers and their daemonic allies.  In the Warhammer 40,000 background, the Ultramarines and Word Bearers are ancient enemies from when they fought during the Horus Heresy.

Ross Watson (game designer): Ross Watson (born May 22, 1975) is a designer of computer, miniature and role-playing games and a writer in various genres.  Watson worked on the Warhammer 40,000 Roleplay line as the Lead Developer for Dark Heresy, was the lead designer for Rogue Trader and Deathwatch, and was part of the design team for Black Crusade.  He was the lead developer for both Aaron Allston's Strike Force and Savage Worlds Rifts.  His written works include the Accursed and Weird War I settings for Savage Worlds, contributions to the Star Wars: Edge of the Empire RPG, and the video games Darksiders II, , and .  Watson has designed rules and scenarios for miniature game lines, such as Dust Warfare, and he has written for several card games, including , Empire Engine, and the Lost Legacy series.

Warhammer 40,000: Rogue Trader: Warhammer 40,000: Rogue Trader is the first edition rule/source book for the Warhammer 40,000 miniature wargame by Games Workshop.  The subtitle refers to a particular class of character within the Warhammer 40,000 universe.

Supporting paragraphs: Ross Watson (game designer) Warhammer 40,000 Roleplay
Answer: May 22, 1975