Microsoft’s Rise of the Tomb Raider exclusivity deal “has a duration”, Xbox boss Phil Spencer has told Eurogamer.

In other words, it’s a timed exclusive – a detail both Microsoft and Crystal Dynamics neglected to mention when they batted the ‘e’ word around yesterday.

Spencer refused to say how long the timed exclusive window is, stating that such a thing wasn’t his job.

"My job is not to talk about games I don't own,” he said.

“I have a certain relationship on this version of Tomb Raider, which we announced, and I feel really good about our long term relationship with Crystal and Square.

"I get the reaction I see. If I'm a PlayStation person all of a sudden I feel like, the franchise has gone. I didn't buy the IP. I didn't buy the studio. It's not mine. Where this thing will go over time, just like Dead Rising or Ryse, we'll see what happens with the game. I don't own every iteration of Tomb Raider.

"I don't own them building Tomb Raider on other platforms. I can't talk about the franchise that way. I can talk about the deal I have."

Spencer did say that Tomb Raider would ship next holiday season (Christmas) on Xbox 360 and Xbox One.

“I'm not trying to fake anybody out in terms of where this thing is. What they do with the franchise in the long run is not mine. I don't control it," he added.

“So all I can talk about is the deal I have. I don't know where else Tomb Raider goes.

"Yes, the deal has a duration. I didn't buy it. I don't own the franchise."

When pressed further on that duration, Spencer again refused to give an answer.

"It's not because I'm trying to be a headfake on anybody. It's a deal between us and the partner.

“People ask me how much did we pay. There are certain things I'm just not going to talk about because it's a business deal between us and them. Obviously the deal does have a duration. I didn't buy the IP in perpetuity.”