The 3D hazard prefab

Assemble the prefab

Create Prefabs/Mob.rprefab with a CharacterBody3D root named Mob and CollisionShape3D / MeshInstance3D children. Use a BoxShape3D and BoxMesh, both Size (0.8, 0.8, 0.8), with a light StandardMaterial3D. Child local positions are 0 and scales are 1.

The root occupies layer 3 (numeric Collision Layer = 4) and detects only floor layer 1 (Collision Mask = 1). Hazards do not block one another. No externally downloaded model is needed.

Complete code

Attach Scripts/SquashMob.cs to the root:

using Reckfell;

public partial class SquashMob : CharacterBody3D
{
    [Signal] public delegate void SquashedEventHandler();
    [Export] public float Speed { get; set; } = 2;
    [Export] public Vector3 MoveDirection { get; set; } = Vector3.Forward;
    private double _age;
    private bool _squashed;

    public override void _PhysicsProcess(double delta)
    {
        _age += delta;
        Vector3 direction = new Vector3(MoveDirection.X, 0, MoveDirection.Z).Normalized();
        Vector3 velocity = direction * Speed;
        velocity.Y = IsOnFloor() ? 0 : Velocity.Y - 24 * (float)delta;
        Velocity = velocity;
        MoveAndSlide();
        if (_age > 10 || Mathf.Abs(Position.X) > 8 || Mathf.Abs(Position.Z) > 8)
            QueueFree();
    }

    public bool TrySquash()
    {
        if (_squashed || IsQueuedForDeletion()) return false;
        _squashed = true;
        EmitSignal(SignalName.Squashed);
        QueueFree();
        return true;
    }
}

Movement

MoveDirection specifies X/Z direction. The vertical component is discarded and the remainder normalized; zero direction leaves the hazard stationary. Speed uses units per second, and gravity keeps the body on the floor. MoveAndSlide() applies the time step.

The controller spawns at Y = 0.4, placing the cube bottom on the floor. Direction toward the player's position is chosen once at spawn and not recomputed. This is straight-line movement, not obstacle-aware pathfinding.

Deletion and score

An instance is removed beyond X/Z = ±8 or after 10 game seconds, bounding its lifetime even when it never meets the player.

TrySquash() returns true once. It sets _squashed before the signal, then calls QueueFree(). A repeat in the same frame cannot award another point. The controller handles Squashed; the hazard does not own score.

Test in Arena.rscene, with its floor, camera and built scripts. See instance spawning.