UPDATE: Microsoft has confirmed to Eurogamer that the Warzone mode found lurking with Gears of War: Judgment is a slice of code leftover from Gears of War 3.
There are no current plans to release the mode - free or otherwise.
"There is a text string and a bit of leftover code within TDM from Warzone," a Microsoft spokesperson told us. "We don't have any current plans to release Warzone. But, we will be releasing Execution, a very similar mode, for free as an update on April 2 via Xbox Live."
ORIGINAL STORY: A playable version of game mode Warzone has been discovered on the Gears of War: Judgment disc.
Players have been able to access and play it using a simple button combination entered on one of the game's menu screens.
Warzone exists as a multiplayer mode in Gears 1, Gears 2 and Gears 3, but was left out of Judgment.
Warzone can be accessed using the following method (and there are numerous video walkthroughs on YouTube):
After booting the game, choose Private Match and highlight Team Death Match, and press A. At the next prompt press the A and B buttons simultaneously. When it says "You are about to start a match. Continue?", press A again.
Gamers who discovered Warzone have been left wondering whether the hidden mode is intended as paid DLC. But an employee of developer Epic Games has suggested its inclusion was simply a mistake - a remnant of game code being ported over from Gears of War 3.
"Thanks for the heads up, was easier to leave Warzone refs than rip out," said senior multiplayer programmer Peter Knepley in response to a fan on Twitter.
"It's not the polished Execution of April 2nd," Kneply continued, referencing another mode due for release. "I'd never say never, but Execution is way more popular than Warzone."
An image posted on NeoGAF appears to show information for a number of extra maps, too. These haven't been proven to exist in playable form on the disc and may just be placeholder entries for future content.
The additional maps are Mausoleum (likely a re-make of the Gears 1 map of the same name), Hospital, Museum, Capitol and Haven.
The latter two have already been announced for release next week as part of a free, Maxim-sponsored download alongside Execution.
Eurogamer has asked Microsoft for comment. We'll update when we hear back.