private void Update()
{
    if (Time.unscaledTime >= nextRefresh) { nextRefresh = Time.unscaledTime + .3f; RefreshWanted(); }
    int budget = 1;
    while (budget-- > 0 && pending.Count > 0)
    {
        var cell = pending[0];
        pending.RemoveAt(0);
        if (wanted.Contains(cell) && !chunks.ContainsKey(cell)) Build(cell);
    }
}

private void RefreshWanted()
{
    wanted.Clear();
    void Include(Vector3 position)
    {
        var center = Cell(position);
        for (int z = -definition.viewRadius; z <= definition.viewRadius; z++)
        for (int x = -definition.viewRadius; x <= definition.viewRadius; x++)
        {
            var p = center + new Vector2Int(x, z);
            if (definition.Biome((p.x + .5f) * definition.chunkSize, (p.y + .5f) * definition.chunkSize, activeSeed) == regionIndex)
                wanted.Add(p);
        }
    }

    if (world.LocalPlayer.mapScene != "Moonshadow") Include(hero.transform.position);
    if (world.IsAuthority)
        foreach (var player in world.State.players)
            if (world.ActivePlayers.Contains(player.id) && player.mapScene != "Moonshadow")
                Include(player.position);

    var remove = new List<Vector2Int>();
    foreach (var pair in chunks)
        if (!wanted.Contains(pair.Key)) remove.Add(pair.Key);
    foreach (var cell in remove) Unload(cell);

    pending.Clear();
    foreach (var cell in wanted)
        if (!chunks.ContainsKey(cell)) pending.Add(cell);
    var focus = Cell(hero.transform.position);
    pending.Sort((a, b) => (a - focus).sqrMagnitude.CompareTo((b - focus).sqrMagnitude));
}