# Advanced Travel System: Tunnels and Ferry Crossings

## Overview
The advanced travel system adds strategic depth to journey planning by introducing special travel options that require player decisions and resources.

## Tunnel System

### Detection
- **Automatic Recognition**: Roads passing through mountain regions are identified as potential tunnels
- **Mountain Threshold**: 3+ adjacent mountain tiles indicate tunnel conditions
- **Pathfinding Integration**: Tunnels appear as special segments in calculated routes

### Travel Options
1. **With Torches** (Recommended)
   - **Speed**: 0.8x cost (20% faster than normal roads)
   - **Cost**: 10 gold per torch required
   - **Safety**: Safe and well-lit travel
   - **Detection**: Player inventory checked for available torches

2. **Without Torches** (Risky)
   - **Speed**: 3.0x cost (200% slower than plains!)
   - **Cost**: Free but dangerous
   - **Risk**: Very slow, potential for getting lost
   - **Experience**: Atmospheric but inefficient

### Player Experience
```
Special Travel Options Available:
Tunnel detected from (15,20) to (18,20)

Options:
☐ Use Tunnel (with torches) - 10 gold, fast travel
☐ Use Tunnel (without torches) - Free, very slow
☐ Use Standard Route - Go around mountains

Would you like to purchase torches for 10 gold?
```

## Ferry System

### Detection
- **Dock Proximity**: Searches for dock tiles within 8 tiles of route endpoints
- **Water Validation**: Ensures 70%+ water between dock points
- **Distance Limits**: 3-15 tile range for viable ferry routes
- **Cost Calculation**: 25 gold per tile + 50 gold minimum

### Ferry Options
- **Speed Advantage**: 0.7x cost (30% faster than going around)
- **Cost Structure**: Distance-based pricing
- **Route Planning**: Automatically suggests ferry when beneficial

### Player Experience
```
Special Travel Options Available:
Ferry crossing available from Port Anchor (12,8) to Harbor Bay (18,15)

Ferry Details:
- Distance: 8 leagues across water
- Cost: 250 gold (25 gold per league + 50 base fee)
- Time Saved: 30% faster than overland route
- Alternative: 18 tile detour through plains and forests

Accept ferry crossing for 250 gold?
```

## Integration Features

### Smart Route Planning
- **Cost-Benefit Analysis**: Compares special options with standard routes
- **Resource Awareness**: Checks player inventory and gold
- **Time Efficiency**: Highlights faster options
- **Player Choice**: Always offers standard route alternative

### UI Components
- **Option Selection**: Radio button interface for travel choices
- **Cost Display**: Clear pricing and resource requirements
- **Inventory Check**: Shows available torches and gold
- **Route Comparison**: Standard vs special route information

### Debug Information
```
=== SPECIAL TRAVEL OPTIONS ===
Tunnel detected from (15,20) to (18,20)
Ferry crossing available from (12,8) to (18,15)
==============================
```

## Terrain Integration

### Updated Movement Costs
| Terrain | Base Cost | With Special Options |
|---------|-----------|---------------------|
| Tunnel (with torches) | 0.8x | Recommended route |
| Tunnel (without torches) | 3.0x | Emergency option |
| Ferry | 0.7x | Water crossing |
| Dock | 0.8x | Port infrastructure |

### Pathfinding Enhancements
- **Multi-Option Routes**: Single destination, multiple travel methods
- **Resource-Aware**: Considers available inventory items
- **Economic Planning**: Balances speed vs cost
- **Player Agency**: Never forces expensive options

## Technical Implementation

### Key Methods
- `CheckForSpecialTravelOptions()`: Analyzes calculated path for opportunities
- `IsTunnelSegment()`: Detects road segments through mountains
- `HasFerryOption()`: Identifies viable water crossings
- `ShowSpecialTravelOptionsUI()`: Presents choices to player

### Resource Management
- **Torch Tracking**: Inventory integration for tunnel travel
- **Gold Management**: Cost verification before travel
- **Alternative Routes**: Always provides free standard option

## Strategic Gameplay

### Decision Making
- **Resource Management**: Spend gold for convenience vs save money
- **Time vs Cost**: Fast expensive routes vs slow free routes
- **Risk Assessment**: Dark tunnels vs safe but longer routes
- **Exploration Rewards**: Finding efficient travel networks

### Economic Impact
- **Trade Routes**: Efficient paths become valuable
- **Resource Trading**: Torches gain strategic value
- **Port Towns**: Ferry access increases settlement importance
- **Mountain Passes**: Tunnel routes create chokepoints

This system transforms travel from simple pathfinding into strategic resource management with meaningful player choices!
