UnrealKismet

UnrealKismet is a Visual Scripting system within the UDK that allows artists that don't possess programming knowledge to create scripted behavior from within levels in a relatively quick and intuitive manner. It has been called a rapid prototype editor, as it is powerful enough in many cases to be used to test out complete gameplay concepts without writing a single line of UnrealScript code.

Example of Kismet Sequence Controlling an Elevator Function

Sequence Objects

Each sequence object is a self-contained black box which performs a single purpose. The types of sequence objects available are:

• Actions - These are objects which perform some action on the Actors in your level.
• Conditions - These do not actually affect the level, but the control flow of your sequence. They make decisions on which output to fire depending on some condition.
• Variables - These objects simply store information of a particular type for use by an Event, Action or Condition.
• Events - These are objects which create an 'input' to your sequence, possibly from an Actor in the game. A common example is the Level Loaded event which fires when the level begins.

For a basic understanding of UnrealKismet, it is highly recommended to visit the UDN pages on the topic, as they are among the best Epic has to offer.

Kismet User Guide

Kismet Reference

Kismet Examples

That said, there's still a lot to be left desired, as it is difficult to learn UnrealKismet on a short guide and reference alone. A more complete Help section may provide insight for the learner.