Alien Zoo Keeper mini-game...
	Bubble gun...
	Change weapon at the beginning...
	Completion bonuses...
	Easy "Smart Pack Rat" achievem...
	Holiday message...
	Puzzle mini-game...
	Rainbow gun...
	Seven way Plasma Gun...
	Various Achievements...

Watch the credits and click all lines that have the letter "O". A sound will confirm each correct click. When the name list ends, wait and another list will begin. Once again, click the lines that have the letter "O". The word "Secrets" will appear. Click it to play the Alien Zoo Keeper mini game.

Start a game and do not shoot for about two minutes while not getting damaged by the aliens.

In survival mode the first or second creature you kill will always have a new weapon power-up. If you do not like that weapon, just wait for it to disappear and kill another zombie for a different weapon to appear. This will happen whenever you have the pistol and there are no other weapons on screen.

Successfully complete the game under the normal difficulty setting to unlock the hardcore difficulty setting and Typ 'o' Shooter mode.

There are two ways to accomplish this. For both, start a co-op game, solo if desired.

Play in Survival mode go on a killing spree. Collect every weapon that is found.

Start a Quest mode map with monster nests (spawns). Have the second player join and survive until there is only one nest remaining. Go on a killing spree at regular intervals, and do not die. Note: Use the Fire Cough perk to dispose of monsters easily without using big guns which can destroy the nest. As long as one player still has the pistol, most kills should spawn weapons, as long as there are not any on screen. Kill as long as possible and eventually blowtorches will spawn. Note: Nests will eventually stop spawning monsters.

Set the system date to December 25. When the game starts, a "Happy Holiday" message will appear with snow. Click on the snow or message to return to normal.

At the "Extras" menu, select the "Credits" option, then scroll to the bottom of the screen to see something is hidden. Press Y(3), X(3), Y to unlock the Puzzle mini-game.

Have your first shot kill an alien with one hit. Walk directly to its body and wait at that location. Allow the other aliens to almost kill you to get the gun. Note: This only works in earlier versions of the game.

This trick allows you to use a "7-way Plasma Gun" and is useful in survival mode. Acquire the Pulse Gun (that shoots little green waves). Get these Perks: Angry Reloader, Fastloader, and Stationary Reloader. Do not get the Perk Alternate Weapon, as this will mess things up. After getting the gun and Perks, hold [Reload]. Seven-way constant shots should start spewing from your weapon. Note: Do not get the Perk Alternate Weapon. Remain still if you have Stationary Reloader and the shots will fire faster. Try this with the "Weapon Power-up". Barrel Greaser and Fastshot will make the shots go faster, but not more frequently.

Complete the following achievements to unlock Microsoft Gamerscore points.

Achievement	How to unlock
Arms Race (50 points)	Get over 100k points in Weapon Picker game mode.
Bloody Good Time (30 points)	Explode 50 creatures to gibs within the first 30 seconds of a level.
Booom (50 points)	Get over 75k points in Nukefism game mode.
Chapter 1 Complete (30 points)	Complete all Quests in Chapter 1.
Chapter 2 Complete (30 points)	Complete all Quests in Chapter 2.
Chapter 3 Complete (30 points)	Complete all Quests in Chapter 3.
Chapter 4 Complete (30 points)	Complete all Quests in Chapter 4.
Chapter 5 Complete (30 points)	Complete all Quests in Chapter 5.
Chapter 6 Complete (30 points)	Complete all Quests in Chapter 6.
Chapter 7 Complete (30 points)	Complete all Quests in Chapter 7.
Club Hardcore (80 points)	Complete the game in Hardcore difficulty.
Feel the Rush (50 points)	Get over 50k points in Rush game mode.
Grim Reaper (200 points)	Beat the game in Grim difficulty.
Home Wrecker (30 points)	Destroy over 500 nests.
Impaler (30 points)	Get 100 percent hit accuracy in Chapter 2 Quest 5.
Little Survivor (30 points)	Get over 250k points in Survival game mode.
Master of Chains (30 points)	Bounce Shock Chain powerup over 30 times.
Mr Survivor (50 points)	Get over 500k points in Survival game mode.
Not a Scratch (30 points)	Complete all Normal Quest levels with full health remaining.
Perky (50 points)	Unlock all Perks.
Quickly! (50 points)	Get over 250k points in Blitz game mode.
Smart Pack Rat (30 points)	Collect 50 Blowtorches.