Nettank

A multiplayer top-down 2D tank battle game where players control tanks and try to destroy each other.

Requirements

• Java: OpenJDK 25 (Java 25) or newer
• Operating System: Windows, macOS, or Linux
• Graphics: OpenGL 3.3 compatible graphics card

Controls

Keyboard (Default)

• W - Move forward
• S - Move backward
• A - Rotate left
• D - Rotate right
• Space - Fire weapon
• Escape - Exit game

Gamepad (Default)

NetTank supports any standard gamepad including:

• Xbox controllers (Xbox One, Xbox Series X/S, Xbox 360)
• PlayStation controllers (DualShock 4, DualSense)
• Nintendo Switch Pro Controller
• Generic USB gamepads

Default Gamepad Mapping:

• Right Trigger (RT/R2) - Move forward
• Left Trigger (LT/L2) - Move backward
• Right Stick (horizontal) - Rotate left/right
• A button (Xbox) / X button (PlayStation) - Fire weapon

Customizing Controls

All keyboard keys and gamepad buttons are fully customizable! See INPUT_CUSTOMIZATION.md for:

• How to rebind keys and buttons
• Adjusting gamepad sensitivity and deadzones
• Example configurations (Arrow keys, ESDF layout, etc.)
• Troubleshooting tips

Game Configuration

Players can customize additional game settings by editing ~/.nettank/game-config.json:

• Player Name - Set your display name (max 20 characters)
• Display Resolution - Default: 1920x1080 (1080p)
• Fullscreen Mode - Toggle fullscreen/windowed mode
• VSync - Enable/disable vertical sync

See GAME_CONFIG.md for complete configuration documentation, including:

• All supported resolutions (800x600 up to 4K)
• Configuration examples
• Troubleshooting tips

Documentation

For Players

• Game Configuration - Display, graphics, and player settings
• Input Customization - Keyboard and gamepad controls

For Developers

• Documentation Index - Complete documentation overview
• Terrain System - Game terrain architecture and features
• Quick Reference - Fast setup guide for terrain system

Launching The Game Client

Note: OpenJDK 25 (Java 25) Runtime or newer is required to run the game client or the server.

The game client is a universal jar file that can be run on any platform with Java installed.

Basic Launch (Quick Start)

java -jar nettank-client/target/nettank-client-0.1.0-SNAPSHOT.jar

Recommended Launch (Best Performance)

For optimal performance with modern Java features:

java -XX:+UseG1GC -XX:MaxGCPauseMillis=50 -Xms256m -Xmx512m -jar nettank-client/target/nettank-client-0.1.0-SNAPSHOT.jar

Parameter Explanation:

• -XX:+UseG1GC - Use G1 garbage collector (low-latency, good for games)
• -XX:MaxGCPauseMillis=50 - Target max 50ms GC pauses (reduces stuttering)
• -Xms256m - Initial heap size (faster startup)
• -Xmx512m - Maximum heap size (prevents excessive memory usage)

macOS-Specific Launch

macOS users need to add -XstartOnFirstThread for LWJGL/OpenGL compatibility:

java -XstartOnFirstThread -XX:+UseG1GC -XX:MaxGCPauseMillis=50 -Xms256m -Xmx512m -jar nettank-client/target/nettank-client-0.1.0-SNAPSHOT.jar

Connecting to a Remote Server

The game client connects to localhost:5555 by default. To connect to a different server:

java -jar nettank-client/target/nettank-client-0.1.0-SNAPSHOT.jar <server_address> <server_port> <player_name>

Example:

java -jar nettank-client/target/nettank-client-0.1.0-SNAPSHOT.jar 192.168.1.100 5555 MyTankName

Or with performance parameters:

java -XX:+UseG1GC -XX:MaxGCPauseMillis=50 -Xms256m -Xmx512m -jar nettank-client/target/nettank-client-0.1.0-SNAPSHOT.jar 192.168.1.100 5555 MyTankName

Launching The Game Server

The game server can be run directly with Java or deployed using Docker.

Running with Java (Direct)

Basic Launch

java -jar nettank-server/target/nettank-server-0.1.0-SNAPSHOT.jar

Recommended Launch (Best Performance)

For production servers with optimal performance:

java -server -XX:+UseG1GC -XX:+UseStringDeduplication -Xms512m -Xmx1024m -jar nettank-server/target/nettank-server-0.1.0-SNAPSHOT.jar

Parameter Explanation:

• -server - Use server JVM (optimized for throughput over startup time)
• -XX:+UseG1GC - Use G1 garbage collector (low-latency)
• -XX:+UseStringDeduplication - Reduce memory usage for duplicate strings
• -Xms512m - Initial heap size
• -Xmx1024m - Maximum heap size (adjust based on player count)

Server with Custom Configuration

Specify port, map size, and network update rate:

java -jar nettank-server/target/nettank-server-0.1.0-SNAPSHOT.jar <port> <network_hz> <map_width> <map_height>

Example:

java -server -XX:+UseG1GC -Xms512m -Xmx1024m -jar nettank-server/target/nettank-server-0.1.0-SNAPSHOT.jar 5555 30 50 50

Parameters:

• port - Server port (default: 5555)
• network_hz - Network update rate in Hz (default: 30, range: 20-120)
• map_width - Map width in tiles (default: 50)
• map_height - Map height in tiles (default: 50)

Running with Docker

Build the Docker Image

docker build -t nettank-server .

Run in Interactive Mode (Foreground)

docker run -p 5555:5555 nettank-server

Run in Detached Mode (Background)

docker run -d -p 5555:5555 --restart unless-stopped nettank-server

Docker with Custom Port

docker run -d -p 7777:7777 --restart unless-stopped nettank-server

Performance Tuning

For high-traffic servers (10+ concurrent players), consider increasing heap size:

java -server -XX:+UseG1GC -XX:+UseStringDeduplication -Xms1024m -Xmx2048m -jar nettank-server/target/nettank-server-0.1.0-SNAPSHOT.jar

For low-resource environments (2-4 players):

java -server -XX:+UseG1GC -Xms256m -Xmx512m -jar nettank-server/target/nettank-server-0.1.0-SNAPSHOT.jar