1.
Quality Co-op Gameplay: Next-gen co-op action from the makers of Half-life, Portal, and more.
2.
AI Director 2.0: Customizes enemy population, effects, and music based on players' performance.
3.
New Melee Weapons: Includes axes, chainsaws, frying pans, and baseball bats for close combat.
4.
Meet 'The Survivors': Features four different survivors, a new storyline, and new dialog.
5.
Xbox LIVE Co-op Support: Achievement points, stats, rankings, and collaborative play support.