Gears of War Walkthrough, Part 1, Act 1: Ashes, Chapters 7 and 8

Enter the room and defeat the Drones attacking you. Proceed to the balcony. Grab the Hammer of Dawn, it's near the door to the balcony. Go outside and use the Hammer to exterminate another Seeder and some more Drones. An ammo box can be found here. Move back into the room and listen to the dialog. The enemies will come through a sealed door to the left. Fight them off, then enter the corridor and turn right. Continue moving and reach another turn, proceed further and you'll find some ammo and a revolver. It's a great and very powerful sidearm, but has only six bullets when fully loaded, so count your shots.

Proceed to the next room and fight off the bad guys here, then continue following your team. Before the turn to left, there's a small room to your right with some ammo in it. Next room will have a Troika gunner at the far end, so run in quickly and dive into a doorway to your right. Fight your way through several linked rooms, and you'll find yourself behind the gunner; I believe you know what to do... Quickly grab the Troika then and lay down fire on the Wretches running through the corridor.

Follow your team, and you will come out in another corridor. Go down to the right if you need some ammo, then turn around and move the other way. Continue running until you reach a room with an ammo box and a shotgun as well as some Drones shooting from the room across. Deal with them, then pick up all the ammunition and grenades and proceed further. Afther a couple of turns, you will find your teammates near the stairs. Go up and listen to the dialogue (or rather, a trilogue) and climb up the next stairway, where another unsuspecting Troika gunner is shooting down at the Alpha team. Shoot him and take the Troika - there are many Drones down the street, so rain fire upon them for good. Sometimes an enemy will take cover and don't come out for a long time, so it can take a while to root him out. You'll be noticed when the fight is over and a cinematic will start.

After the cinematic, pick up the Hammer where you stand and the tenth COG tag near your unfortunate teammate, then run to the opposite direction through the rooms until you find the Berserker. Now, this is one of the most challenging opponents you'll face and requires good reflexes. Shooting at it is pointless; do it only when you need to attract the beast's attention. Berserker basically attacks by charging straight at any source of sound, therefore you can avoid it by moving slowly and silently. A Berserker's charge is an instant death, but it can be avoided by dodging to side in the last moment (double-tapping left or right movement button). Also, if this opponent runs into something hard, like a wall, it will be stunned for few seconds, giving you the time to change your position. Also take note that the Berserker will kill a teammate if he is down, which means that you have to get the beast's attention before it is too late.

So avoid the enemy's charge and get out of the corridor by exiting through the door to the right. At the far end of this room is a closed door - trick the Berserker to smash into it. Get through the door, take the ammo if needed and proceed further. Repeat the same trick with door smashing in the next room. In the far left corner of this room you can find the eleventh COG Tag. Another smashable wall to lure the enemy into is just to the right of it.

Continue moving and lure the Berserker outside. Here you can find the twelfth COG Tag near the end of the wall to the left as well as finally finish the enemy with the Hammer of Dawn. Use the weapon when the opponent is stunned after running into an obstacle, and it shouldn't take too long to win this fight. Your victory will signal an end to Act 1.