I. A Brief Tutorial on Thief Data Files

Thief keeps its game data packed in "resource" files with the .crf extension.  Examples are easy to find on your CD, and some resource files may be copied to the directory where you installed Thief.  These resource files are compressed using the "zip" compression format, and may be managed just at if they were .zip files by any compatible compression application.

No such application is included with DromEd, but they are available widely on the net as shareware, with very reasonable registration agreements.  It’s possible to change Thief configuration without ever editing these .crf files (see below), but
you’ll really want a zip archive program to let you browse through the existing data. These resource files are packed versions of a varying number of original source files, complete with directory paths.  To change this data you can either edit the version of the file in the resource archive, or you can simply create a file with the same name and directory path under the directory where you installed Thief.  If such a file exists it will be used in preference to the version in the .crf file.  This is the key to modifying your Thief install without doing any permanent damage to the default installation that lets people play the normal Thief missions.  You can make your own resources to override the .crf files without actually editing the originals, and when you’re done with your "modification" you can just delete the local resource files and let Thief see the versions in the .crf again.

II. Text for Mission Objectives

For example, suppose you want to actually have the mission objectives for your new mission appear on the Objectives screen with appropriate text descriptions (fancy that).  Assuming you’ve installed the English version of Thief, the file that contains these descriptions is in the intrface.crf archive.  It’s called miss/english/goals.str, where miss is the actual name of the mission in question.  So, let’s start by looking at mission names.

Each mission has an ID number n and a name of the form "missn."  The filename of the mission file should be the same as this mission name, with a .mis extension.  So, if I wanted to make a new mission and call it mission 15, I’d use the filename miss15.mis, and place that file in the main Thief directory.  There’s also a couple of pieces of data you have to set in DromEd to correspond to this mission number.  On the Editors menu, select "Mission Parameters…"  On the resulting dialog, select "Dark Mission Description" and click OK.  The resulting dialog will have a field you can fill in for "Mission Number" and "Mission Pathname."  So for mission 15, I’d fill in "15" in the first field and "miss15" in the second.  Mission numbers outside the normal mission sequence (i.e. 15 and up) are a good idea because the filename of your new mission will not conflict with that of any shipping Thief mission.

Now, getting back to setting text for the goals of my new mission.  Any of the existing goals.str files in the intrface archive will serve as an example.  Open one of them with a text editor, like Wordpad, and you’ll see that for each goal ID number there’s a "fiction" string and a "text" string.  The "fiction" string is used in the pre-mission briefing, while the "text" string is used in the in-game Objectives screen.  Usually the "text" versions are shorter, since we need to do less explaining, and space may be tight if we’ve added objectives since the beginning of the mission.  If you want, you can make both strings the same, as long as everything fits on the Objectives screen.

To set objective text for my new mission 15, I make an intrface sub-directory of my Thief directory (if there isn’t one there
already).  Under that, I make a sub-directory called miss15.  Under that, I add an  english directory (actually, in any case where a language-dependent subdirectory like this is called for, I can omit it, and all that will happen is that I’ll get the same resource no matter what language I’ve installed Thief in).  Now I write up a goals.str file, using any text editor (such as Notepad) and put it here.  Now, when I load mission 15 in DromEd and go into game mode, I can go to the Objectives screen and see my new text for these mission objectives. The mission directories in the intrface resource also contain data files for the map which appears on the in-game Map screen.  Thief requires some of this data.  This document covers how to set up a PCX format image to be displayed on the in-game Map screen.  A blank page is provided with DromEd as page001.pcx.  To make your own map will require a paint program capable of editing PCX files.

Each map page is a separate file in the intrface resource, named pageddd.pcx, where ddd is some three-digit number.  Number pages sequentially, without gaps.  Mission quest variables are used to indicate which pages to look for. You should create variables named map_min_page and map_max_page whose values indicate the highest- and lowest-numbered page present.

Setting up Thief to highlight Garrett’s current location on the map is outside of the scope of this document.

III. Playing New Missions from Thief

Suppose you want to be able to play a newly-created Thief mission without using DromEd to load in the mission file.  By running the mission from Thief itself you can set difficulty levels, purchase loadout, and trade the new mission with your friends who may not have DromEd themselves.  Also, any difficulty-dependent changes in the mission layout (using "Difficulty/Delete" and similar object properties) will be processed automatically when you go into the mission, without your having to issue a separate process_difficulty command in DromEd.

Setting up Thief to run a new mission is actually rather easy: only one data file needs to be changed. Take a look at the file missflag.str in the strings.crf archive.  Each mission can have a number of these "flags" describing how it fits into the mission sequence, allowing for example it to skip its loadout or briefing movie.  Unless you’re going to make your own briefing movie, the "no_briefing" flag will be very handy!  Note how there’s also a flag which allows a mission to be skipped entirely, as you will see was done with the mysterious mission 8.

To set Thief up to play my new mission 15, then, all I have to do is make a strings subdirectory in the main Thief directory, and place a missflag.str file in it.  This will override the version in strings.crf.

To start with, I just copy the file from the .crf archive.  Edit the flags for every mission so that they are the same as mission 8: "skip" and no other flags.  Then I add a new line for mission 15, as follows: miss_15: "no_briefing,end"

Now, if I start Thief and select New Game, it will skip all of the usual Thief missions and start me at mission 15.  If I had created a whole sequence of missions I could just add them as missions 16, 17, etc. and only set the "end" flag for the last mission.  Whenever I finished a mission in the sequence I would automatically proceed to the next one, just like in the real game.

Actually, you may want to leave mission 1 alone, since that’s the training.  If you do decide to "skip" mission 1 in the missflag.str file, then whenever you load up Thief and select the training mission, you will instead be taken to the custom mission you created.

Subsequently, if you choose to "skip training," you will still be taken to the custom mission.  So, regardless of whether or not you choose to play the training mission in Thief, you will be taken directly to the custom mission if you included in the missflag.str file the "skip" parameter for mission 1.

When you’re just starting out, you may also want to add the "no_loadout" flag and skip setting up a "Store" of objects for the
player to purchase.  Setting up a "Store" is much like setting the player’s starting inventory, but is outside of the scope of this document.

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