In the days of yore i.e. circa 1999, the Marathon devs at Bungie were working on a game codenamed "Project Phoenix," before the studio was acquired by Microsoft and shifted all its efforts toward Halo, leaving the abandoned Phoenix unable to rise from the ashes.
Now, for the first time, Bungie's Jason Jones has peeled back the curtain, explaining that this canned project was a "Minecraft-like" strategy hybrid.
"It was a game that was based on a technology that was sort of Minecraft-like," Jones said in an interview with IGN. "You could build castles out of blocks, for example, and then knock them down. Ultimately the reason the game never saw the light of day was because of Halo. The [Project Phoenix] team got scavenged a number of times, both on Halo 1 and Halo 2, to finish Halo."
"It was able to render things like Minecraft," he continued. "It was cool. There were big castles and you could knock them down with trebuchets. Knocking holes in the wall, and dudes would come out."
He added that Project Phoenix had RTS elements, but ultimately the team had a hard time pinning down exactly what it wanted Project Phoenix to be, and so the studio focused its efforts solely on Halo. "It was trying to find out what it was, and it hadn't," said Jones. "It made it very clear at several junctures, 'Well, should we put all the resources on the team behind Halo, or should we keep working on this game?' Eventually we made the decision that it was Halo. The team just went away, or the project went away. The people are still here."
Elsewhere in the interview, Jones admitted that a week before its E3 2004 appearance, the Halo 2 demo "was running at a steady five, ten frames per second." Now that must've been scary.