World of Warcraft lead systems designer Greg “Ghostcrawler” Street has left Blizzard to take on a “new and exciting” opportunity elsewhere.

Street announced his departure on Facebook.

“I have been at Blizzard Entertainment for almost six years. It has been epic and I have made many friends around the world and I have learned so much. But, I have a great opportunity for something new and exciting, and sadly it is time to move on.

“The game community will likely find out today, so I wanted you all to hear it from me first.

“To all of you in my Blizzard family, inside the company and out, thank you for everything. We will keep in touch. You have made me love my life.”

Street came to Blizzard in 2008 from Ensemble, where he had worked on the Age of Empires franchise.

Blizzard announced a new World of Warcraft expansion, Warlords of Draenor, at BlizzCon earlier this month.

“Across Draenor's savage jungles and battle-scarred plains, Azeroth's heroes will engage in a mythic conflict involving mystical draenei champions and mighty orc clans, and cross axes with the likes of Grommash Hellscream, Blackhand, and Ner’zhul at the height of their primal power,” writes Blizzard. “Players will need to scour this unwelcoming land in search of allies to help build a desperate defense against the old Horde’s formidable engine of conquest – or else watch their own world’s bloody, war-torn history repeat itself.”

The expansion will increase the character level cap to 100, and will bring fully revamped character models and animations to the aging MMO. In addition, lapsed players will be able to boost one character to level 90 in order to get into the new content without playing through older content.