Editing: The Very Basics
What is editing? Put very simply, editing an existing retail game means you can use what's included with the game (art and programming assets) and modify them to your own liking. One example would be using the art for Episode 3 and creating your own deathmatch map to run around and play in. This is a very simplistic example, of course, and depending on how technically proficient and persistant you are you could concievably create a whole new game. People do this, in fact, and have been doing so for years. What most people end up doing is creating their own singleplayer and multiplayer maps, but people also create new skins, models, or even huge modifications that completely change the gameplay.
TEXTURE A flat piece of art that is wrapped by the game around models or level walls, in order to make it look like something.
Implementing the console in Daikatana
What is a console? In games powered by the quake engine, there is a method of passing commands and variables straight to the engine through a command-line-like interface. This interface is called the 'console', and is activated by hitting the tilde key (~), which is up next to the one (1) button.
How do I activate the console? Running Daikatana normally means you cannot access the console. In order to get it, you have to use the +set console 1 command-line parameter when first starting up the game. This can be done several ways.
Once you are in Daikatana and can bring down the console by hitting ~.