Update: The reference to a new Thief game was still in place on the Straight Up Films website when Anfossi tweeted about it, but it has now been removed. The sentence that previously referred to "a fifth sequel" now says only, "Thief is widely considered to be one of the greatest games ever created."
Original story:
A rumor went around last week, inciting joy or dismay depending on how you feel about these things, that a new Thief game might be in development. It came to us courtesy of the website of Straight Up Films, a production company working on the Thief movie that was revealed last year, which says, "Widely considered to be one of the greatest games ever created, a fifth sequel is currently in development to be released in step with this motion picture adaptation."
Square Enix, which published the 2014 flop-ish Thief reboot, declined to be nailed down about it one way or the other, saying in an email, "We don't have anything to announce at this time." Eidos Montreal studio head David Anfossi was a bit more on the nose about it today on Twitter, however.
The tweet leaves the door to a new game open at least a crack. A different studio could be making it (especially if it turns out to a free-to-play movie tie-in for mobiles), and "forget it" could be meant in the way that's usually accompanied by, "... if you know what's good for you." Also possible? That there's not actually a new Thief game coming at all. I will keep listening (like a thief) and let you know if I hear anything else, but right now is sounds like this particular rumor needs to stay on the "very iffy" pile.