Achievements...
	Game modes...
	Saving survivors...

Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
A Week To Live ( 25 points )	Complete 7 days in any game mode without dying.
Anniversary of the dead ( 45 points )	Complete the Final Day, in either Single or Multiplayer, and finish the game.
Can't Touch This ( 20 points )	Rack up a 100x multiplier in any game mode.
Environmental Awareness ( 5 points )	Kill a zombie using an environmental hazard in any game mode.
Friends in Low Places ( 20 points )	Save 25 survivors in any game mode.
Gas Powered ( 5 points )	Complete an entire arena, getting every kill with the Chainsaw.
Gun Shop ( 5 points )	Kill at least one zombie with each weapon type in any game mode.
Hotter Than Hell ( 25 points )	Complete the final day of the "7 Days of Hell" unlockable mode.
Interior Decorator ( 20 points )	Kill 25 zombies in any game mode using environmental hazards.
More the Merrier ( 10 points )	Kill 10 or more zombies at the same time in any game mode.
Socialite ( 5 points )	Play in an online multiplayer game.
Tour of the City ( 15 points )	Complete each arena at least once in the same game in any game mode.

Complete the indicated task to unlock the corresponding modes. Note: All modes are unlocked after Day 55 is completed.

7 Days Of Hell
Unknown. This mode consists of seven very long levels with a different graphics effect.

All Weapons
Unknown. In this mode you can use any weapon with unlimited ammunition. Press Left or Right to scroll through the weapons.

Blackout
Unknown. In this mode your view is limited to a small circle around your character. The circle expands when more players are near. Also, radioactive zombies become very visible.

Chainsaw Only
Complete a level with all kills done with the chainsaw. You cannot have any environmental or Zombie Bait. In this mode you are limited to the chainsaw and Zombie Bait.

Hardcore
Survive seven days with no deaths. In this mode you only have one life and cannot gain any more.

Turbo
Get a 100x multiplier. In this mode everything moves faster.

Stand next to survivors and throw a teddy bear in a safe direction to distract the zombies.