The lights are on
A playable version of Warzone mode has made its appearance on the Gears of War: Judgment disc and has been labeled as being leftover code from Gears of War 3.
"There is a text string and a bit of leftover code within TDM from Warzone," a Microsoft spokesperson told Eurogamer. "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."
Warzone was a multiplayer mode in the first, second and third installments, but it was left out of Judgment. In order to access the Warzone mode, you can follow these steps.
After turning on the game, pick Private Match and highlight Team Death Match, and press the A button. When the next screen comes up, press A and B concurrently. When the text says "You are about to start a match. Continue?", press A again. If you are more of a visual learner, there are a number of different Youtube tutorials as well.
There are no immediate plans to release the mode.