Blade Runner does not have an inventory like traditional adventure games. A Clue Database serves as the repository for all relevant information and objects collected throughout the course of the player's investigations. You can filter through this massive amount of information by case, suspect, and a variety of other options.
The above screenshot shows a list of clues concerning a suspected Replicant Clovis in the Animal Murder case, the first case undertaken by the player. Clovis has also been implicated in other cases, and selecting those will show a different list of clues. To see all clues associated with Clovis you would select the Suspect tab. With a half dozen suspects and as many cases, you can see why proper filtering tools are necessary.
This database contains everything from physical objects collected at the crime scene to interviews with other characters. Each piece of evidence can be examined or listened to by clicking on it. What's notable is that you generally can not use any of these collected items to interact with objects in the game environment. This is not an inventory designed to help organize items that the main character will use to overcome puzzles. The clue database is designed to organize evidence that the player will use to piece together the game's mysteries. Blade Runner is not about solving puzzles that serve as obstacles preventing quick progress through the narrative. The gathering and examination of clues is the puzzle. As you play a detective character, it is the narrative. What do these graceful and limping footprints mean? Where will all this evidence collected from the car accident lead us? These are not items we give to a character to unlock a new area, they are clues we use to piece together an idea of what happened, in our head. The traditional point and click adventure game has an almost physical wall between its ludological and narrative halves. Blade Runner does not acknowledge the existence of this wall. The clues serve the player's fabula as much as the game's ludological requirements for progression and puzzle solving. A very progressive design for a game made in 1997.
On occasion these clues can be used in a more traditional role -- showing a photo to a witness, discovering a computer password -- but these are the exception to the rule. If you have a photo of Clovis, for example, and speak to a character on the street, you will automatically show the photo and ask if he looks familiar. There is no guessing what clues this character will respond to through trial and error. These are all very logical and activated through dialogue choices, so it always feels like the game is anticipating player actions instead of taking control away
With no real puzzles and automatic item interaction you might be wondering where the challenge lies. The game demands and rewards thoroughness. In other games this might be disparagingly called "pixel-hunting", but in Blade Runner it is "investigation". If you do not want to click all over a crime scene, or speak to suspects and witnesses over and over until you're sure they've revealed all they know, then a detective game of this sort may not be what you're looking for. There are, however, two types of traditional puzzles - Esper photo enhancement and the Voigt-Kampff test. These require little explanation, as they work exactly as you would expect them to. In the former, find the hidden clue; in the latter, the Replicant giveaway. There is also combat (It's a Blade Runner game, you will retire Replicants!), and it is possible to die. The game is challenging, the solution to the mysteries not so obvious, and the fear of accidentally retiring a human always hanging over your head. It's an unexpected and welcome feeling, that hesitation when someone you question runs off and you have the option of shooting them in the back or chasing them. The game mechanics don't offer any hints and make both options viable in the moment. Chase down the alley or shoot in the back? Unless you want to go with gut instinct and face the potential consequences of a wrong guess, you'll need to carefully study the evidence you've collected in preparation for these moments requiring quick decision.