Game Currency and The Store
The currency in Dead Space is credits which are acquired as pickups also scattered around the game's environment. Credits can also be acquired by selling items at stores, one or more of which are located on each level, or chapter as it were, of the game. A visit to the store also allows you to stash items in the safe where it can be later retrieved at any other store.
The game economy is similar to that we've seen in previous games of the genre (Resident Evil 4 comes to mind) so there's not much new here. Thankfully you can purchase power nodes to make upgrades anytime you please and although the various weapons and armored suits are gradually made available for purchase at the store throughout the game by locating special schematics, once available, the entire upgrade tree for each weapon or item becomes available at the bench.
This allows those who hoard ammo (and eventually collect much more than they need) to sell the excess, buy power nodes and use them to progress more rapidly through any of the item upgrade trees.
I forget where but in my travels I read somewhere that Dead Space doesn't really scare you but rather startles you and I would have to respectfully disagree. Unlike, say, FEAR 2 where the scare factor is hit-and-miss, I feel that Dead Space truly terrifies. Yes, the game does indeed suddenly spring aliens on you throughout your journey but it's what happens in between that creates a genuinely chilling experience and this is very much due to the magnificient job the developers did on the sound.
The USG Ishimura really feels like it —and/or something besides you— is alive out there and as poke your way through its passageways, it clangs, it hisses, it whirs and otherwise continually emits unidentifiable 'lurking' sounds that seem innocuous enough but have an uncanny way of keeping you totally on edge. Even the sound effect of your holographic map opening sounds suspiciously like the snarl of a little monster off in the distance. Add in the periodic screams of unseen victims, the growls of aliens victimizing them (or preparing to do the same to you) and, of course, some requisite ominous music and you have an atmosphere that you really feel compelled to approach with caution at the very least.
And approach with caution you do. Often throughout the game, an alien will suddenly race by in front of you and disappear around a corner seemingly lying in wait. And you soon find out (typically the hard way) that the aliens use the ships venting system as a means to get around which makes finding a safe place to stand and fight a precarious task. As a matter of survival, you'll eventually learn to carefully scan your immediate surroundings looking for any and all vents which could possibly give birth to another neck-gnawing alien attack.
One thing I'm amazed at is how Dead Space manages to spook you without keeping you in the dark (once again, pun intended) as to where your next objective is. Whereas other survival horror games seem to thrill in keeping you floundering about in uncertainty battling off monsters while you try to figure out where to go next, Dead Space does the opposite and tells you exactly where to go next.
Not only does the game provide a holographic zoomable/pivotable map of your current environment with a path clearly marked from your current location to the next objective but it also provides a special Locator system you can use anytime in-game, that is, not while in some kind of game menu but actually in the game. With the simple press of a key (or button), Isaac will turn sideways and a special light blue line will be drawn on the floor of the ship showing you precisely where to proceed.
I felt this system was handled a lot more aesthetically than the equivalent in Bioshock (which had a go-this-way arrow constantly displayed near the top of the screen and was on by default all the time until a patch was released to make it optional).
The Locator system does have one shortcoming though and that is it is actually so easy to get around using it that you tend to ignore the map feature altogether thus creating a kind of tunnel vision as you proceed through Dead Space. Relying solely on the Locator eventually gives you the feeling that you don't really know ultimately where you're going or where you've been but rather only that you're supposed to go that way. About halfway through Dead Space, I actually started to ween myself off the Locator and force myself to use the map more in an attempt to truly familiarize myself with each of the game's twelve levels.