Bungie was not happy about Halo Wars using its IP, calling it “the whoring out of our franchise”, according to Ensemble Studios founder Tony Goodman.

Although Bungie lacked the means to make the game itself, it nevertheless was unhappy with it being worked on by another studio, he said.

"Bungie was never up for it... [it] was kind of sore about the idea.”

“That didn't create a great relationship between us and Bungie; they viewed us as someone infringing."

The game was never supposed to be a Halo title, but Microsoft – feeling nervous about releasing a real-time strategy game onto its console – insisted the Halo brand was attached to it.

“The difficult part of that was it took the game back about a year in development, and I think it never quite turned out the same. They just said, 'Why don't you just paint over what you have with Halo stuff?' But things aren't quite that simple," said Goodman.

Halo Wars was released in 2009, and was the final game created by Age of Empires developer Ensemble Studios.