Overview of Kismet
While UnrealScript can cover fundamental game mechanics, Kismet works with level-specific functionality such as opening doors or reacting to game events, such as the death of the player, in ways specific to that level.
As an example, in our game, if we wanted to have the weapon upgrades spawn in specific locations when we killed a boss, we would use UnrealScript to create generic Kismet actions and events. Some of the events and actions we would need for this purpose already exist, so in the end we would have a mix of stock and custom Kismet in our game.
A simple introduction
Before we start getting into the UnrealScript side of things, let's take a look at some things we can do with the Kismet that's already present.