Dead Space is a popular game from EA. The PC version is the only one without a controller, which gives it different cheats than the console versions.
Access the Cheat Code Menu
Once your game has started, you must pause it to use the cheats. Use the keyboard to enter the following codes.
Type X,X,Y,Y,Y to refill your oxygen. Type X,Y,Y,X,Y to refill both stasis and kinetic energy. Type them in correctly or they will not work.
Type Y,X,X,X,Y to add two nodes to your game. Typing Y,X,Y,X,X,Y,X,X,Y,X,X,Y will add five nodes. Use X,X,X,Y,X to add 1,000 credits to your wallet, X,X,X,Y,Y to add 2,000 credits, X,X,X,Y,X,Y to add 5,000 credits and X,Y,Y,Y,X,X,Y to add 10,000 credits.