One of my favourite titles just because it's such a solid game, Dead space is a third person shooter with an emphasis on horror and action. The game nails atmosphere and variety and has some very interesting mechanics that set it apart from other games.
Let's start with dismemberment system. Every enemy in the game can have its limbs blown off by careful aim, this can slow the enemy down or disable its ability to effectively attack you, and sometimes it just strait up pisses the enemy off or makes them harder. It encourages players to approach every enemy differently from the last and to land their shots with deadly precision to cause maximum damage.
The game also features an inventory system, each item takes up one slot so players need to ration how much ammo and health they take with them since they may find items such as schematics to create new weapons or other items they can take back to a store that would take up space. This space doesn't include weapons like other inventory systems however all items have the same space value. It greatly simplifies things so players don't need to waste time in the inventory or worry the weapons they carry will get in the way of other items they may need.
The level design should also be written about as it constantly pushes the player forward and rarely lets them get lost thanks to clever P loops and a great map system. Many of the areas are just hubs that branch off to the objectives players need to complete and almost every level ends back where is begun on the monorail system. All the levels have small secret areas and such to find as well so players are encouraged to travel off the beaten path. It all adds up to a very good title that rewards skill, intelligence and exploration.
Weapon balance: You can beat the whole game with just the plasma cutter without much difficulty, also for a game about blowing the limbs off enemies there is a shockingly large number of weapons that fail to do that effectively at all. There isn't much I can suggest to fix this since the plasma cutter serves its job so damn well, it's versatile, it's damaging, it's quick, it's cheap and it's easy to use. The other weapons all have their own roles but since the plasma cutter covers most of these roles as well, the other weapons just seem situational or for variety. It's just rather disappointing to find a new schematic, buy the new gun; finally get to use it, upgrade it in hopes of it being better and then realising you're best sticking with the default weapon.
Health packs: They are the only way to heal and will do so instantly without much cool down. The problem is because there is no alternative way of healing health packs lose value as something to save because there is absolutely no reason to ever let yourself fall below maximum health. The bar on your back and every medpack in your inventory makes up your collective health, this also makes the health upgrades you can get seem rather worthless as they only serve to increase the healing power of the full heal medpacks. An easy fix would have been to put a short cool down between medpack usages this would encourage players to be careful in the middle of a fight since they would be unable to instantly heal up to maximum health with the medpacks in their inventory.
Upgrading: You upgrade weapons and armour with power nodes, however not every point you can sink a power node into will upgrade the weapon, this means players have to waste power nodes to get to the upgrades they want. This also means it's possible to fully upgrade a weapon using only the minimum amount of power nodes by following an optimised route. Looking at it it's actually a way of carefully increasing the cost of certain upgrades but it would have been nice to unlock a special ability on weapons you have fully upgraded because as it is, the weapons only serve to get stronger they never become more interesting to use. In "Resident Evil 4" players not only chose what weapons to upgrade based on weapon preference but what the special ability of that weapon would do to it once upgraded.
Power nodes: These can be found around the ship in blue wall mounted boxes, there also gotten as rewards for defeating hard enemies or completing mini-games. You can also buy them from the store; this undermines their value and rarity. Money isn't a hard resource to come across in Dead space, and by the end of the game you will find yourself with so much excess ammo and medical supplies that it's easy to just sell all of it for a huge cash injection you can spend on power nodes to upgrade weapons. I would have liked to have seen the power nodes as a resource that should be carefully managed and not wasted, a reward for skill and exploration, not something to throw money at.