Chapter 1 - Dead Space 2
You'll start off without any weapons so just ignore what's going on around you and run (press LB). There's only one path so just continue running until a necromorph jumps on you. Just keep pressing A to push it away. Continue forth to find the first save station. Follow the straight path until you reach the monitoring room upstairs.
Continue along until you get attacked by a deranged personnel. After releasing you from your straight jacket, open the wall locker as he suggested and grab the health pack and the flashlight. Use the health pack immediately.
Take the elevator next, then go through the dark room. After exiting to the corridor, there's an audio log (Popsicles) on the floor next the locked door to your right. Follow the corridor then save the game.
Go past the shower room then crawl into the maintenance vent. After falling into the operating room, approach the panel to the left and deactivate it. You'll have access to your first ability, the Kinesis Grab. Grab one of the rods there and shoot the glass to the left. Two necromorphs will approach you so use the rods to pin them on the wall.
Take the elevator and grab/use the health pack inside. In the next room, more necromorphs will attack you so use the nearby rods to kill them. Before leaving the area, make sure to crush the necromorph corpses to get more loot. Exit through the door and destroy the corpses in the hallway to get credits.
Exit to the next operating room and loot the wall lockers in the individual rooms. Don't bother going through the tied up necromorph by the door since you'll only get damaged. Enter the operating room and activate the terminal. You'll obtain your first weapon, the Plasma Cutter here. Shoot the two necromorphs that will attack you. Disable the head of the tied up monster to kill it.
Exit to the next room, then follow the hallway. Grab the 1000 credits in the room to the left. Take note that three necromorphs will attack you after the fire control system triggers.
Before entering the next room, check the wall locker in the waiting room to the right, and a plasma kit from the body by the chairs. Enter the next two rooms and grab the items inside until you reach hallway. Before heading to the next objective, check the room to your left to find a text log (Orderly TPS Report 1411).
After grabbing the log, check the waiting area before moving to the objective to grab some items. Once you've reached the lockdown area, you'll need to fight off some necromorphs before you can move on. After the lockdown lifts, enter the lobby and grab the Power Node, ammo and a text log (Anxiety Spike)
Enter the next hallway and save at the save station. In the next room, you'll have to hack the panel, slow down the charging necromorph and kill it while it's slowed down. Grab the text log (Heisenberg) on the floor on the right corner. Open the door using the panel in the middle of the room. You can't exit immediately so stasis the door then run past it.
Head to the next room where you'll find two acid-spewing necromorphs. Get rid of them then open the two wall lockers and grab the Power Node on the table nearby.
Take the elevator up to the Patient Care area. After reaching the area, check behind the counter to obtain a text log (Secrecy) and a Power Node. The Conduit Room nearby contains another log but it can only be accessed if you have a save file of the arcade game Dead Space Ignition. The same applies to all Conduit Rooms you'll find from hereon. If you can't access them, you can just ignore them.
Head to the next room and the hull will be breached. Shoot the red triangle above to close the breach. Head to the next room where you'll find a save station, a store and another Power Node. There's a necrom playing possum on the floor so don't let it catch you off guard. Shoot it before it ambushes you. Access the store to grab your first rig and sell or store some of your extra stuff.
Exit to the vacuum and quickly find the other end of the path. Here, you'll find a large room and your first encounter with a large necrom. Use stasis on it and shoot the glowing orange parts of its limbs. There's a nearby stasis recharge station just in case. After taking down the enemy, grab the loot and backtrack to the store to sell some of them (especially the semi-conductor) then save the game.
Take the other door leading to the maintenance bay. Search the room for items then use kinesis to move the panel ahead. Enter the maintenance vent.