When items are randomly generated, it becomes easier to withhold information about them from the player. A game can have various kinds of identify systems which encourage the player to either experiment with items to determine their use, or acquire objects which allow these items to be identified.
While an Identify game mechanic is possible with a fixed set of game items (as with Nethack or XCom), in such cases a player can use visible aspects of the item to google a full description of its attributes. Therefore an Identify System is not necessarily a procedural content algorithm, but it is most powerfull in PCG games.
Identify not required, fixed item list:
These games use a system where an item can be used without identifying first. Though there is a fixed set of possible items the descriptions are varied between games.
In most of these cases there is a technique that players learn (frequently through spoilers) that will let them know which items are which, but they don't know right off since the appearance of each item is randomized (Purple potions aren't flaming potions since this one didn't start my sword on fire …). There may be some exceptions for armor and weapons, and sometimes there is some interaction between the description of an item and its properties (e.g. a ring that appears simple and gold might be corrosion resistant no matter what the ring actually does, while a clay or paper ring would dissolve in acid).
Identifiy required, variable items:
These games have unpredictably varying item attributes, but require the player to identify them before use.
In these cases it doesn't matter so much that a player can't guess the function of an item, the item can't be used until it is identified. Note that in none of these games are the items cursed - such items would be pointless because they would never be used.
Identify required, fixed items:
Here not only are the items fixed, but their appearance is as well. Identify is still required before use.
- X-Com requires that alien artifacts be researched before they can be used. The artifacts are always the same, and even a new player might guess what a weapon does because the aliens have used them against the player.