Gears of War 4 Horde 3.0 Details; New Class System and Defense Building Revealed - GameSpot

Gears of War 4's Horde mode will feature a class-based system, defense building, and cards.
Gears of War 4 is the next installment in the Gears of War series and is exclusive to the Xbox One.

Horde Mode Tips and Tricks - Gears of War 4 Guide - IGN

Horde Command Pack, Gears of War Wiki

Gears of War 4, Gears of War Wiki

E3 2011: Gears of War 3 – Everything you wanted to know about Horde 2.0 but were too terrified to ask. – Nerd Appropriate

Interview: In detail with Gears of War 4's Horde Mode 3.0 designer

Gears of War 4's Horde mode is more intense than ever before

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Horde Mode Tips and Tricks - Gears of War 4 Guide - IGN

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Gears of War 4 Review - GameSpot

Gears of War 4: Rise of the Horde is Largest Update Ever, Free, and Out Now - Rocket Chainsaw

Gears of War 4 Review - GameSpot