AceField/Scripts/Logic/World.cs

using Godot;

namespace AceField.Scripts.Logic;

public partial class World : Node2D
{
    [Export] public PackedScene PlayerScene;

    public void StartGame()
    {
        if (!Multiplayer.IsServer())
            return;

        // Handling player connect / disconnect after this client connected
        Multiplayer.PeerDisconnected += RemovePlayer_Adaptor;
        Multiplayer.PeerConnected += AddPlayer_Adaptor;

        // Handling player connected before this client
        foreach (var id in Multiplayer.GetPeers())
            AddPlayer(id);

        // Add this client as a player if client isn't a dedicated server
        if (!OS.HasFeature("dedicated_server"))
            AddPlayer(1);
    }

    public override void _ExitTree()
    {
        if (!Multiplayer.IsServer())
            return;

        Multiplayer.PeerDisconnected -= RemovePlayer_Adaptor;
        Multiplayer.PeerConnected -= AddPlayer_Adaptor;
    }

    private string BuildPlayerName(int id)
    {
        return $"Player#{id}";
    }

    private void AddPlayer_Adaptor(long id)
        => AddPlayer((int)id);

    private void RemovePlayer_Adaptor(long id)
        => RemovePlayer((int)id);

    private void AddPlayer(int id)
    {
        var player = PlayerScene.Instantiate<AceField.Scripts.Player>();
        player.SetPlayerId(id);
        var position = Vector2.FromAngle(GD.Randf() * 2 * Mathf.Pi);
        player.Position = new Vector2(position.X * 5f * GD.Randf(), position.Y * 5f * GD.Randf());
        player.Name = BuildPlayerName(id);

        AddChild(player, true);
    }

    private void RemovePlayer(int id)
    {
        var name = BuildPlayerName(id);
        if (!HasNode(name))
            return;

        GetNode(name).QueueFree();
    }
}