FISSION Item Modding Mini-Guide

Add a Custom Weapon, Armor, or Misc Item

This guide assumes you have a working mod folder (e.g., mods/mod_mytown.dat/ from the Quick Start Guide). You’ll add a new item that can be placed in the world, given to the player, or used in scripts.

1. What You Need

Your existing mod folder: mods/mod_mytown.dat/. (a folder for development, compress into actual .dat for release)

You will create two new files for your item:

• proto/items/items_mytown.lst – lists your custom item file(s)
• text/english/game/pro_item_mytown.msg – provides name and description

Plus the actual .pro file – you can export it from the Mapper or copy and modify an existing one.

2. Create the Proto Definition File

File: mods/mod_mytown/proto/items/items_mytown.lst

myweapon.pro

Each line is the name of a .pro file (without path). You can add multiple lines for several items.

Optional Overrides

After the filename, you can add key=value pairs to override certain fields:

myweapon.pro fid=120 inventory_fid=250

3. Create the Message File

File: mods/mod_mytown/text/english/game/pro_item_mytown.msg

Each item gets two consecutive entries: name and description.

{0}{}{Laser Sword}
{1}{}{A deadly energy blade.}
{2}{}{Plasma Rifle}
{3}{}{Fires superheated plasma bolts.}

• The first item (myweapon.pro) will use offsets 0 (name) and 1 (description).
• The second item (second line in .lst) would use offsets 2 and 3, etc.

Note: The base ID for these messages is generated automatically from your mod name (mytown) and the type (item). You don’t need to calculate anything.

4. Where to Put the .pro File

The .pro file must be placed in the same folder as the .lst file:

mods/mod_mytown/
        └─ proto/
            └─ items/
                ├─ items_mytown.lst
                └─ myweapon.pro

How to get a .pro file:

• Option A: Use the Mapper → open the Proto Editor, create a new item, save it as myweapon.pro in the mod’s proto/items/ folder.
• Option B: Copy an existing vanilla .pro (e.g., from proto/items/) into your mod folder and rename it. The PID inside the .pro file is ignored – FISSION generates its own stable PID from the mod name and filename.

5. Test Your Item

1. Run the game once.
2. Check data/lists/proto_list.txt – your item should appear under “ITEM MOD PROTOS”.
3. Find the generated PID (e.g., 16843034). You can now use it in scripts:

variable item_pid;
item_pid := 16843034;   // use the number from proto_list.txt
create_object(item_pid, 0, 0);

Or give it to the player:

add_obj_to_inven(dude_obj, item_pid);

6. Important Notes

PID generation is stable – the same mod name + proto name always produce the same PID. You can safely hardcode the PID from proto_list.txt in your scripts.

The PID inside the .pro file is ignored – do not worry about what number it shows.

Hash collisions – if two different mods accidentally generate the same PID, a warning message box appears and the second item is skipped. Rename your mod or proto to resolve.

Message IDs – each item uses two consecutive IDs (name, description). The base ID is allocated per mod, so you never need to assign numbers manually.

7. Quick Troubleshooting