Blizzard's unannounced MMO has been in development for years, World of Warcraft's game director has revealed.

Speaking exclusively to VideoGamer.com, Tom Chilton, game director for current MMO king World of Warcraft, also confirmed that he is involved in development of the mysterious project, and is "excited" by it.

Word of the game first emerged in December 2007, when a job listing looking for artists to work on a "next-gen MMO" popped up on Blizzard's website.

Last month World of Warcraft community manager Zarhym posted on the official forums confirming the game will be a "brand new franchise".

He said: "We have nothing to advertise for the new MMO because it's a shell of a game thus far. We've already stated it'll be a brand new franchise, which means the lore, art, and game play are being developed entirely from scratch. It's an overwhelming process, but a process through which we excel. Our track record supports this."

The news put paid to rumours that the game was Universe of StarCraft.

When asked about the game by VideoGamer.com at the Warcraft Regional Finals 2009 tournament in Cologne, Germany, Chilton remained cagey.

"Certainly I've gotten to see a lot of what's gone on," he said. "I've been participating in it for a long time now. But it's definitely not anything that I can talk about. It's not anything I can give any insight into or any hints or whatever."

He did, however, confirm that he's "been involved for years now" with the game, and that the game has, "to a certain extent, on a very small scale", been in development for years also.

In February 2009 WoW game director Jeffery Kaplan announced he shifted positions from WoW to the unannounced MMO.

When asked if Blizzard's fans should be excited by the game, Chilton replied: "I certainly hope so. I'm excited about it so hopefully they will be too."

Interestingly, Chilton told us that he agreed with comments from EverQuest lead designer Ryan Barker, who told VideoGamer.com earlier this month that WoW, which enjoys an eye-watering 11.5 million monthly subscribers and is currently the world's largest MMORPG, will eventually be dwarfed.

Barker said it will probably be "something totally different that we haven't even thought of yet", and suggested social networking site Facebook as inspiration.

Chilton, however, said he hoped Blizzard itself would be the developer to dwarf WoW.

"I definitely do think there will be some MMO at some point that beats WoW, that's bigger than WoW," he said. "Hopefully we're the ones that make it, but whether that happens, I don't know."

Could Chilton be referring to the unannounced MMO he's working on?

What do you think Blizzard's unannounced MMO will be? Let us know in the comments section below.

Carry on the conversation on the VideoGamer forums!