For a detailed survival RPG, the data that needs to be managed can easily become overwhelming if approached in an ad hoc manner.
First, you may want to do away with HP and instead have a system of wounds, where various body parts can be specifically injured and each injury requires individual attention. Attacks can be targeted and the effect of an injury depends on its location and how well it is treated.
The next obvious step is to manage clothing so that each piece of clothing covers particular body parts and provides particular armor values to each part. We also need to keep track of clothing conflicts, where two pieces of clothing try to cover the same area and so they can't be worn together, except when they are designed to be worn under or over other clothing.
In addition, there could be magical effects on certain body parts, or perhaps claws or spikes could be added. Perhaps various limbs could be replaced by cyborg parts, or magical parts. Even worse, perhaps there are creatures alternate body plans with more or fewer than the usual limbs.
Each limb can be divided into parts, so for example a leg consists of a thigh, a knee, a lower leg, and a foot. We want to manage those parts individually, but we also want to remember that together they represent a leg. We might need this so that targeted attacks aren't forced to be overly specific and we can provide players with notifications that doesn't give excessive detail.
For example, in the game "Slaves to Armok" you can sometimes get messages about some particular toe, finger, or ear being hit. This is clearly too much detail for the middle of battle. We wouldn't want be forced to give that sort of detail because we're not storing the fact that these detailed parts add up to a greater whole. At the same time, a strict hierarchy of parts wouldn't be right, because two arms together make up "the arms" of a character, yet each arm individually is part of either the "the left side" or "the right side" of the character, and we'd want to keep track of these relationships so we can provide appropriate messages to the player.
We'd also want all this data to be stored sparsely. For example, if you're facing twenty goblins, there's no point in individually storing every limb and detail for each goblin when they are all identical. We want to store a prototypical goblin in one place, then each individual goblin can be represented only by how it differs from the prototype. Further, the prototype goblin could be represented by how it differs from the prototype human. This is not just to save memory, but also to allow the game to know what makes each character special so it can give the player relevant messages. The game could mention "the goblin with the head wound" or "the goblin with the spiked glove" because that's exactly how those goblins are represented in memory.
Obviously one shouldn't jump blindly into designing such a game, solving each problem as it arises. This level of complicated data needs a database-style system to keep all the details organized, yet a simple relational database doesn't provide an obvious solution. Could something like an Entity System be the right approach?
Is there a known strategy for managing this sort of data that experienced game developers would always use for making this sort of game?
