Part of a good game may always be how the AI enemies react. An article on AIGameDev goes behind the scenes of Thief and looks what makes it tick.
[A] sensory system is a pipeline for managing information about events that occur in the game. If you implement this right, it shouldn’t be limited to any of the human senses. You can easily fake any kind of sensation by pushing information into the pipeline at the right place.
Meaning: you are not limited to the human senses, you can make up any data and feed it into the system.
Sometimes though, you need to make the system dumber than it actually is:
“Most interesting is the snippet that restrains the AI’s ability to see the player until seen by the player, which is purely for coordinating the player’s entertainment.”
As a matter of fact, the game’s difficulty level can be adjusted by making the NPCs more predictable in their reactions and/or stating their current state clearly.
But then again: Is this really necessary? Can’t we assume grown up players that have learned to deal with missing information and ambiguity?
Unfortunately, as a second article about Halo 3’s AI system shows, have gamers a tendency to
attribute the easy parts to poor AI and the hard parts to evil level designers.
The Halo 3 paper has another 40 tricks how to make the player believe that there are intelligent agents acting.