In part 4 of Dark Carnival, look for a strength-testing game in the first area after exiting the safe room. Inject some adrenaline and nail the red button with a melee weapon to get the Gong Show Achievement (be "stronger than Moustachio"). Note: Will summon infected!

In part 4 of Dark Carnival, look for well-lit Whac-A-Mole-like arcade game near the start. Activate the button on the front of it and attack the Moustachios that pop up with a melee weapon. At a score of 46, the game will break -- you may need to continue a few times. When it breaks, you'll get the Stache Wacker Achievement (be "faster than Moustachio"). Also, the game will attract zombies.

In part 2 of Dark Carnival you'll come across a well-lit shooting range with carnival mascot Moustachio emblazoned on it. Also note the yard gnome in the box -- your prize for getting 750 points. Get this high score by activating the game (via the red button) and shooting everyone but the blue peanut (you'll lose points if you hit this target!). Hit the yellow and green Moustachio target for extra points. The gnome (which you may recognize from Half-Life 2 Episode 2) will be released if you get a high score and so will scores of infected, so beware!.

Carry the gnome all the way to the end of the scenario (board the chopper) to unlock the Guardin' Gnome Achievement. You can drop Gnome Chompsky and pick it back up. You can also drop it in a safe room and it will be there after the break. Finally, you can use the gnome to repel zombies as you would with a weapon.

Check the gunshop in Dead Center (first episode, second map) for an accurate description of every firearm in the game (except the grenade launcher).