You really shouldn’t need any help for the prologue, but here it is anyways.
Hold the right stick down to use your locator and navigate through the snow storm. Once things come into focus, follow the path along the edge of the cliff until you see the crashed ship. Next to the ship are some green and yellow supply boxes, stomp on them and collects their contents to get some ammo.
Reload and shoot the center of the door that has been iced over, then open the door. Shoot the waster necromorphs that come through the door armed with ice picks. They will charge you, so make sure you backpedal while shooting them. Aim for the limbs with these guys, take out their arms if possible.
Enter the crashed ship. Around the corner is a water who will charge you. Don’t worry about conserving ammo here, just blast these guys away. After taking a second right turn, another waster necromorph, with a broken lower half, will crawl toward you. You can shoot him or stomp on him. A little further down the hall a couple more wasters will charge you. Again, backpedal and fire. After you kill these guys, stomp on them for ammo and move on.
While approaching the ladder on your left, you will see a hanging body be snathced up. Go up the ladder (don’t worry, nothing is gonna jump out at you) and open the door to the cockpit. Enter the cockpit and you will pick up a blue, metal object.
On cue the ship will start to fall. You hook a latch to the ship and start to propel yourself down the icy cliff. Use the run button to move quickly and dodge incoming objects by strafing left and right. Once on the ground the ship will start falling down on top of you. Aim for the flaming orange parts and shoot them to blast a hole in the ship for yourself to slide through. Once you’ve reached the bottom the prologue will be over. Moral of the story is: Never trust strange generals.
Who gave these Unitologists guns? Take and use the medpack in Isaac’s apartment, then exit out the front door. Go around the corner and open the big, red door to meet up with the soldiers. No sooner does your ride show up, then Unitologists will start shooting at you. Don’t waste time returning fire, just head for the police car.
Upon getting to the police car, a suicide bomber will blast it to oblivion, sending Isaac into a hole (this is a strangely built city). Once you get ahold of Isaac, enter the room to your left if you are facing away from the road. You might want to hurry, as grenades will reign down on you pretty soon.
Inside the first room, four soldiers will take cover and shoot at you. Find some cover of your own and return fire at them. The plasma cutter can do some serious damage here. After the room is clear, collect ammon and head out. Upon exiting the room a suicide bomber will charge you. Shoot him to set off his bomb.
Follow the road until you see a ladder on your right. Take the ladder up to a supply room. In this room there are a couple green and yellow supply boxes. Use kinesis to smash them and check the supply cabinets on either side of the exit door.
Through two doors you will see a woman shot by a couple of Unitologists. One is on your level, probably taking cover in the center of the room and another in on an upper ledge to your left. Avenge the woman, grab the ammo the lower Unitologist drops, and follow the hall to the left.
A Unitologist is waiting for you around the corner here. He will pin you down, but be run over by oncoming traffic. Use your stasis to slow down the traffic, causing an accident (you’re supposed to be saving humanity, Isaac). Continue across the street and climb the ladder.
Cross the bridge up here to find a couple supply cabinets. There’s also a supply box on the ground, around the corner opposite the supply cabinets. After you gather these supplies, run across the bridge, and exit through the door.
Run down the hallway and open another door. This will lead you into a cheery, little room, with the leader of Unitologists giving you a nice pep-talk. Run to the back of the room where you will find three supply cabinets. Facing the elevator, there is another (harder to find) cabinet on the left wall. Now take the elevator up. This will trigger a cutscene.
Article from Gamersyndrome.com