Play the Game

Flaggi is a local multiplayer capture-the-flag game. There is no public server, so one player runs the server and the others connect to it with the client.

Tip

If everyone is on the same machine, use localhost:54321. If you are on a LAN, use the host machine’s local IP address instead.

What you need

• A running server
• One client for each player
• A copy of the release build or the repository source tree
• TCP port 54321 and UDP port 54322 open on the server machine

Fastest way to start

1. Start the server

If you downloaded a release build, launch the server JAR directly:

Server terminal

java -jar Flaggi-server.jar

If you are running from source, the helper script builds the server automatically and launches it for you:

Server terminal

./scripts/run.sh server

[!IMPORTANT] Start the server first. The client will not connect until the TCP listener is available.

2. Start the client

Client terminal

java -jar Flaggi-client.jar

Or, from source:

Client terminal

./scripts/run.sh client

3. Connect

In the client menu, enter the server address and your username.

Situation	Example address
Same machine	localhost:54321
Same Wi-Fi / LAN	192.168.1.50:54321
Different network	Use a VPN or port forwarding

Controls

• WASD or arrow keys to move
• Space, F, or mouse click to shoot
• Capture the enemy flag and bring it back to your base

What happens after you connect

1. The client opens a local UDP listener.
2. It sends a TCP hello with your username and UDP port.
3. The server assigns a UUID and replies with the server UDP port.
4. The client switches to the lobby and then into the match.

[!NOTE] The game uses TCP for setup and gameplay events, and UDP for fast per-tick state updates.

Troubleshooting

• Can’t connect: make sure the server machine address is correct and the port is 54321.
• Nothing happens after launch: check the server terminal for logs.
• The client closes immediately: make sure you are using a full JDK/JRE release, not an incomplete install.
• Two clients on one machine: this is supported; each client keeps its own UDP listener.