Fallout 2 Custom Patch Tutorial (revised on Feb 7, 1999)


In this doc I will outline the steps to make a custom patch
of FO2. First you can try my custom patch (this seems to work with
FO2 1.02D patch, English version):

1. Copy CREDITS.TXT to C:\FALLOUT2\DATA\TEXT\ENGLISH\
   In this context, C:\FALLOUT2 is always the FO2 directory. Create
   appropriate sub-directories if necessary. For example, you have to
   first make a directory called TEXT under C:\FALLOUT2\DATA, then
   ENGLISH under C:\FALLOUT2\DATA\TEXT

2. Copy PRO_ITEM.MSG to C:\FALLOUT2\DATA\TEXT\ENGLISH\GAME\
   Do just the same as step 1.

3. Copy 00000397.PRO and 00000013.PRO to C:\FALLOUT2\DATA\PROTO\ITEMS\
   Do just the same as step 1.

4. We must prevent FO2 from deleting our patch. Use any hex editor,
   search "DeleteFileA" in FALLOUT2.EXE and change it to
   "CloseHandle". Note that they are case-sensitive.
   If you don't want to modify FALLOUT2.EXE, you can change attribute
   of above files to read-only.

5. Run FO2. At the main screen where there are INTRO,NEW GAME,LOAD GAME,
   OPTIONS,CREDITS,EXIT options, choose CREDITS and see.

6. Choose NEW GAME and check the stats and description of spear in your 
   inventory.

7. If you have a YK42B Pulse Rifle in your inventory, check its stats. Its
   damage points, range, weight, action points in combat mode, max ammo
   load, damage type, ammo fired per shot in burst mode
   are significantly improved.

If above does not work, check C:\FALLOUT2\FALLOUT2.CFG: find the line
beginning with "master_patches", make sure the correspondent value is
C:\FALLOUT2\DATA

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Now let's see how these patches are made. Prerequisite tools are:

   1. F2RE, the FO2 Game Data Extractor, from my web page
   2. WinZip. Version 7.0 works well. Older version should have no
      problems
   3. gzip v1.2.4. This utility is easy to find. Use archie or
      www.download.com to get it.
   4. UltraEdit 32. (If you have other great hex editor, skip this.)

I will not give details on hacking FO2's decompressed game data files
as my F2RE document has showed you a direction. There are two types of
patches: compressed and decompressed. I'd like to take the spear as the
compressed example:

1. Extract proto\items\00000013.PRO by using F2RE:

    F2RE E:\MASTER.DAT -s items\00000013.PRO

2. Decompress proto_items_00000013.pro.gz by WinZip.

3. Use any hex editor to modify proto_items_00000013.pro as you wish.
   Bear in mind that most values are in big-endian instead of Intel
   80x86's little-endian fashion.

4. Backup proto_items_00000013.pro.

5. Use gzip to compress proto_items_00000013.PRO by:

    GZIP -9 proto_items_00000013.PRO

   This will generate proto_items_00000013.prz. If your gzip doesn't
   support Win95 long filenames, the filename will probably be
   proto_~1.prz.

6. We must change the header so FO2 can recognize the format.
   Use UltraEdit to edit proto_items_00000013.prz. Modify the leading
   10 bytes so they looks like this:

   1F 8B 08 00 00 00 00 00 00 03

7. Delete the bytes that represents original filename. This filename is
   null-terminated, so the trailing 00 must also be eliminated.
   Now the header should looks like this:

   1F 8B 08 00 00 00 00 00 00 03 63 60 .......

8. Rename proto_items_00000013.prz to 00000013.pro and copy it to
   C:\FALLOUT2\DATA\PROTO\ITEMS\

9. Done! Now run FO2, choose NEW GAME and see whether it works.


The decompressed patch is much easier. The example is 
C:\FALLOUT2\DATA\TEXT\ENGLISH\GAME\PRO_ITEM.MSG, the item description
file. You can use any text editor to modify it. Here are the steps:

1. Extract text\english\game\pro_item.msg by using F2RE:

    F2RE E:\MASTER.DAT -s pro_item.msg

2. Decompress text_english_game_pro_item.msg by WinZip.

3. Edit it as you wish.

4. Rename text_english_game_pro_item.msg to pro_item.msg and copy it
   to C:\FALLOUT2\DATA\TEXT\ENGLISH\GAME\

5. Done! Now run FO2, choose NEW GAME and see whether it works.
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by Borg Locutus

Email: dystopia@iname.com

Homepage of this tutorial: http://140.112.31.133/~Borg/f2/

Above email address accepts English and Big-5 Chinese, but don't expect
swift responses from me since I am on active service and have very limited
Internet access.