King's Quest IV: The Perils of Rosella - Interaction Documentation

A comprehensive documentation of all game interactions extracted from the decompiled SCI (Sierra's Creative Interpreter) source code. This project documents the logic, conditions, state changes, and dependencies for recreating King's Quest IV as a modern point-and-click adventure.

Repository Structure

/
├── rooms/                          # Room-specific documentation (one directory per room)
│   ├── kq4-001-beach/             # Beach (starting room)
│   │   ├── 001-beach.md           # Room documentation
│   │   ├── pic_001_visual.png     # Background visual
│   │   ├── pic_001_control.png    # Control (walkable areas)
│   │   └── pic_001_priority.png   # Priority (z-ordering)
│   ├── kq4-002-meadow/            # Meadow (with Satyr/Pan)
│   ├── kq4-010-forest-path/      # Forest Path
│   └── ...                        # One directory per room
├── docs/scripts/                   # Non-room script documentation
│   └── non-room-scripts.md        # Core, region, and interaction scripts
├── KQ4_v1.006.004_int0.000.502_SRC_(6)/
│   └── src/                        # Decompiled SCI scripts
│       ├── Main.sc                 # Game engine & global handlers
│       ├── Game.sc                 # Core game classes
│       ├── Feature.sc              # Object interaction framework
│       ├── InvI.sc                 # Inventory system
│       ├── rm1.sc - rm99.sc        # Room scripts
│       └── *.sc                    # Various utility scripts
└── README.md                       # This file

Source Code Overview

File Types

• .sc files: Sierra Script source code (main logic)
• .sco files: Compiled script object files (not human-readable)
• game.sh: Header file with game constants and defines

Key Source Files

File	Purpose
Main.sc	Global game state, inventory, death handlers, sound management
Game.sc	Core Game class, save/load system, event handling
Feature.sc	Base classes for interactive objects (Feature, View, Actor)
InvI.sc	Inventory item definitions and display logic
Class_255_0.sc	Low-level system procedures and kernel functions
rm##.sc	Individual room scripts (rooms 1-99)
*Reg.sc	Region scripts (shared logic for multiple rooms)

Room Script Anatomy

Each room script (rm##.sc) typically contains:

Room## of Rm                    # Room class definition
├── Properties
│   └── picture                 # Background image number
├── Methods
│   ├── init()                  # Room initialization
│   │   ├── north/south/east/west  # Exit directions
│   │   ├── horizon             # Walkable area boundary
│   │   ├── setRegions:         # Apply shared region logic
│   │   ├── Props/Actors/Views  # Interactive objects
│   │   └── gEgo positioning    # Player start position
│   ├── doit()                  # Per-frame logic (rarely used)
│   ├── handleEvent()           # Text parser input handling
│   └── dispose()               # Cleanup when leaving room
└── Instances
    ├── Scripts                 # Multi-step sequences
    ├── Props                   # Animated objects
    ├── Views                   # Static scenery
    └── Sounds                  # Audio effects

Game Systems

Parser Commands

The original game uses a text parser with verb-noun structure:

• Said 'look/grass' - Player typed "look at grass"
• Said 'use/key' - Player typed "use key"
• Said 'take/diamond' - Player typed "take diamond"
• Said '[<around][/room]' - "look around" or "look room"

State Management

Global variables track game state:

Variable	Purpose
gEgo	Player character object
gRoom	Current room instance
gPrevRoomNum	Previous room number
gInv	Inventory collection
global100	Unknown flag (weather/time?)
global101	Room has been visited
global116	Story progression state
global105	Multi-path room state

Inventory System

Items referenced by index in gInv at: ##:

Index	Item
1	Diamonds
17	Fishing pole
...	(others documented per-room)

Message System

Text displayed via Print scriptNum messageNum:

• Print 1 0 = Message 0 from script 1
• Messages stored separately in RESOURCE files
• To be extracted and added to room documentation

Looking Up Text in the Strings Directory

Message text is extracted and stored in the strings/ directory:

File Pattern	Contents
strings/script_XXX_strings.txt	Script-specific strings (room names, object names)
strings/text_XXX.txt	In-game dialog and message text

To look up a message:

1. Identify the script number from the Print command (e.g., Print 2 1 = script 2, message 1)
2. Open strings/text_XXX.txt where XXX matches the script number
3. Find the entry with the matching message number (e.g., [0001])

Example:

Print 2 1  →  Look in strings/text_002.txt, line [0001]
Result: "You see a river in the distance to the north."

Note: Message numbers in the code start from 0 and are displayed in brackets (e.g., [0001] = message 1).

Room Documentation Format

Each room file follows this structure:

# Room ##: [Room Name]

## Overview
- **Room Number**: ##
- **Picture**: ###
- **Region**: [Beach/Forest/Castle/etc.]
- **Exits**: North→#, South→#, East→#, West→#

## Objects

### [Object Name]
- **Type**: Prop/View/Actor
- **Position**: (x, y)
- **View**: ### (sprite/animation resource)
- **States**: [list of possible states]

#### Interactions

**Look**:
- Condition: [when visible]
- Text: "Message from game"
- Logic: [simplified state check]

**Use [Item]**:
- Condition: [inventory check]
- Effect: [what happens]
- State Change: [global or local variable changes]

## NPCs

### [Character Name]
- **Type**: Actor
- **Behavior**: [wandering, stationary, scripted]

#### Dialogue
- **Greeting**: [initial interaction]
- **Topics**: [what player can ask about]
- **Conditions**: [when available]

## Scripts

### [Script Name]
- **Trigger**: [what starts it]
- **Steps**: [sequence of actions]
- **State Changes**: [what it modifies]

## Walkthrough Integration

- **Critical Path**: [essential interactions]
- **Optional**: [side content]
- **Deaths**: [ways to die in this room]

Conversion Notes for Point-and-Click

When adapting to a KQ5-style interface (walk, look, hand, talk, inventory):

1. Walk: Automated - player clicks destination, character walks there
2. Look: Maps to Said 'look/object' commands
3. Hand: Maps to Said 'use/object', Said 'take/object', Said 'open/object'
4. Talk: Maps to Said 'talk/person' or Said 'ask/person/about'
5. Inventory: Click item, then click target (replaces Said 'use/item/on/target')

Simplifications Made

• Auto-walking: No manual positioning needed
• Context-sensitive: Combine look/take/use based on object type
• Smart defaults: Auto-select appropriate verb for known object types
• Inventory drag: Drag item to target instead of typing commands

Message Extraction Status

Status	Description
⏳ Pending	Text resources not yet extracted from RESOURCE.### files
📝 Documented	Text added to room files

Text messages referenced as Print scriptNum messageNum will be extracted from the game's RESOURCE files and added to each room's documentation.

Generating Room Visuals

Each room directory contains rendered PNG images of the game's PIC resources:

Using sci_pic_render

./sci_pic_render <room_number> "<path_to_game>" <output_directory>

Example:

./sci_pic_render 1 "King's Quest IV - The Perils of Rosella (1988)/KQ4" rooms/kq4-001-beach

This generates three PNG files in the room directory:

• pic_###_visual.png - The background visual
• pic_###_control.png - Control (walkable areas)
• pic_###_priority.png - Priority (z-ordering)

Directory Structure

rooms/
├── kq4-001-beach/
│   ├── 001-beach.md           # Room documentation
│   ├── pic_001_visual.png    # Background
│   ├── pic_001_control.png   # Walkable areas
│   └── pic_001_priority.png  # Z-ordering
└── kq4-010-forest-path/
    └── ...

Contributing

When adding room documentation:

1. Read the corresponding rm##.sc file
2. Document all handleEvent interactions
3. Note all Props, Views, and Actors
4. Track state dependencies (global variables)
5. Include original text when available
6. Describe simplified logic for point-and-click adaptation

Progress

Room Number	Room Description	Status
001	Beach	DONE
002	Meadow (with Satyr/Pan)	DONE
003	Fountain Pool	DONE
004	Ogre's Cottage Exterior	DONE
005	Forest Grove	DONE
006	Cave Entrance	DONE
007	Fisherman's Shack Exterior	DONE
008	Back of Fisherman's Shack	DONE
009	Shady Wooded Area	DONE
010	Forest Path	DONE
011	Enchanted Grove	DONE
012	Haunted Forest	DONE
013	Beach	DONE
014	Green Meadow	DONE
015	The Frog Pond	DONE
016	Graveyard	DONE
017	Spooky House Exterior	DONE
018	Cemetery	DONE
019	Coastal Cliffs	DONE
020	Meadow	DONE
021	Bridge Over Stream	DONE
022	Gnome's Cottage	DONE
023	Forest Path with Cottage	DONE
024	Waterfall and Pool	DONE
025	Beach at River Delta	DONE
026	River Meadow	DONE
027	Forest Path	DONE
028	Mine Entrance	DONE
029	Dense Forest	DONE
030	Mountain Pass	DONE
031	Open Ocean	DONE
032	Ocean Near Island	DONE
033	Enchanted Island Beach	DONE
034	Island Beach	DONE
035	Island Beach	DONE
036	Island Garden Pond	DONE
037	Fairy Island	DONE
038	Island Garden	DONE
039	Island Beach	DONE
040	Island Beach (East)	DONE
041	Island Shore	DONE
042	Fisherman's Cottage Interior	DONE
043	Desert Island	DONE
044	Inside Whale	DONE
045	Genesta's Bed Chamber	DONE
046	Tower Stairway	DONE
047	Genesta's Palace Entry Hall	DONE
048	Ogre's Bedroom	DONE
049	Ogre's Cottage	DONE
050	Ogress's Kitchen	DONE
051	Ogre's Closet	DONE
052		N/A (doesn't exist)
053	Seven Dwarfs' Bedroom	DONE
054	Seven Dwarfs' Cottage	DONE
055	Seven Dwarfs Diamond Mine	DONE
056	Seven Dwarfs' Diamond Mine (West)	DONE
057	Witches' Cave	DONE
058	Tower Organ Room	DONE
059	Baby Nursery	DONE
060	Bedroom	DONE
061	Tower Stairs	DONE
062	Bedroom	DONE
063	Attic	DONE
064	Old Dining Room	DONE
065	Old Kitchen	DONE
066	Secret Tower	DONE
067	The Parlor	DONE
068	The Foyer	DONE
069	The Crypt	DONE
070	Waterfall Cave	DONE
071	Cave Entrance	DONE
072	Dark Cave Passage	DONE
073	Cave Exit	DONE
074	Troll Cave	DONE
075	Troll Cave Passage	DONE
076	Dark Chasm	DONE
077	Swamp	DONE
078	Swamp Island	DONE
079	Mountain Path to Dark Castle	DONE
080	Lolotte's Castle Entrance	DONE
081	Edgar's Tower Bedroom	DONE
082	Lolotte's Tower Bedroom	DONE
083	Castle Dungeon Cell	DONE
084	Cottage Front	DONE
085	Dark Tower Stairs	DONE
086	Dim Hallway (West End)	DONE
087	East End of Hallway	DONE
088	Stone Tower Stairs	DONE
089	Castle Kitchen	DONE
090	West Tower Bottom	DONE
091	Castle Dining Room	DONE
092	Lolotte's Throne Room	DONE
093	Bottom of East Tower	DONE
094	Unicorn Stable	DONE
095	Fisherman's Pier	DONE
096		N/A (doesn't exist)
097		N/A (doesn't exist)
098	Transitional Room	DONE
099	Transitional Room	DONE

Non-Room Scripts

In addition to room-specific documentation, this project also documents the game's non-room scripts including core system scripts, region scripts, and interaction scripts.

Category	Description	Documentation
Core System	Main.sc, Game.sc, Feature.sc, InvI.sc, Sound.sc, etc.	Non-Room Scripts
Region Scripts	BeachReg.sc, Forest Region.sc, GhostWander.sc, etc.	Non-Room Scripts
Interaction Scripts	PlayFlute.sc, ShootBow.sc, ReadBook.sc, etc.	Non-Room Scripts
Special/Cutscene	Intro.sc, CopyProtect.sc, EndMusic.sc	Non-Room Scripts

Credits

• Original Game: Sierra On-Line (1988)
• Decompilation: Unknown decompiler tools
• Source Code: King's Quest IV v1.006.004
• Documentation: Created for remake project

License

This documentation is for educational and preservation purposes. King's Quest IV is a trademark of Sierra On-Line/Activision.