watch the hole in the floor."

Follow this Left 4 Dead walkthrough for 'Watch the Hole in the Floor' to navigate the sewers, avoid alarms, and find the pawn shop safe house.

Once the coast is clear, run up the stairs. Smokers and Hunters may emerge from the windows, so keep your ears open and your eyes peeled. The dark passage across from the stairs may hold some nice weapons or items. When you finally kill every Infected, enter the safe house to find ammo and another stash of upgraded weapons; if you wanna switch your weapon out, now is the time. The level doesn't end here like the demo did, so you must continue your quest.

Exit the safe house and down the hall. The side rooms may or may not contain goodies, so it's up to you to check them. If you have a hunting rifle, you can use it to snipe many Infected from the windows of the rooms. Either way, continue down the hall and down the stairs, eventually exiting the building.

There are plenty of Special Infected here. Like in the last level, Hunters and Smokers will be on the rooftops and scaling the sides of buildings. Continue down the street, killing Infected as you go.

There aren't many places to explore here aside from an alley that leads into a warehouse. This warehouse will take you into a small building and eventually leads to the opposite side of the street. It's a lot better fighting Infected in here than out in the open.

Just past a semi-truck is a red car that has an active alarm. Watch out for the alarm unless you want the Horde on your tail. I highly advise you to prevent the alarm from going off at all costs. There is almost always a Witch nearby, and accidentally startling her is the last thing you want to do.

Make your way into the pawn shop; the neon signs easily give its location away. Quickly speed inside and cram yourself into the safe house to complete the level.

THE SEWERS

Pack your stuff at the safe house and head on out. The area in front of you is a big square, so go either left or right. If you choose to go left, stray from the building and instead move around in a circle to make sure you've eliminated all threats. There is also a garage in the northeast corner that may hold some upgraded weapons or ammo.

Enter the building once the search is complete. You'll soon realize you're in a fast food joint. Go around the counter and shoot any Infected you come across. You may want to check behind the registers or in the bathroom for pain pills or hand-tossed weapons.

Once ready, empty out into the street and use the overturned cars as cover when fighting the Infected. Check the garage on the right for enemies and goods.

Tip: It's pretty important to check your surroundings and do a little exploring when in large areas. Look to the right of the gas station to spot a few wooden cylinder things that you can jump on. Continue up onto a blue dumpster and through the window of the building. You will usually find pipe bombs, molotov cocktails, and pain pills.