Before it was cancelled, the Halo MMO "was absolutely going to compete with WoW" according to ex-Ensemble employee and current Windstorm president, Dusty Monk.
Monk, who was working on the MMO codenamed 'Titan' between 2004 and 2007, revealed details on the game recently:
"We were using a heroic stylised artform," Monk said. "This heroic stylised artform is exactly the artform that you see being used in Star Wars: The Old Republic right now. It's timeless. It doesn't age itself like a game that's built with a strictly realistic artform does."
"We had this idea of quests where you could participate and pull them together without having to be on the same team," he added. "This would be a public quest that everyone in a particular area could work on. That idea went into Warhammer Online."
Monk clearly saw a lot of potential for the MMO saying, "We had all this incredible talent, we had the right people, the right passion, we had a phenomenally successful IP - the Halo IP." But it was a change within Microsoft that lead to the potential World of Warcraft challenger.
"They were looking really hard at the Nintendo Wii and they were really excited by the numbers that the Wii was turning," explains Monk. "So part of this changing of the guard at Microsoft came along with the changing of the attitude to this very expensive, very long and very protacted $90 million USD project we were working on. To cut a long story short, Titan was closed down"
Bungie are currently working on Halo Reach, which they claim 'surpasses many finished games' already, even though it's only in its beta stage.