I made an orbital camera controller for someone who wanted help on the Godot Discord channel. Here’s the source. When applied to a Camera Node it gives this kind of behavior:

	extends Camera
	export var follow_target_path:NodePath = ""
	var follow_target:Node
	export var follow_distance:float = 5.0
	export var follow_height:float = 1.0
	export var mouse_sensitivity_x:float = 0.005
	export var mouse_sensitivity_y:float = 0.005
	var last_mouse_delta:Vector2 = Vector2()
	var mouse_accumulator:Vector2 = Vector2() # The reason we have this instead of using the mouse.position is 'cause when we capture the camera, this will always be 0.
	func _ready():
	follow_target = get_node(follow_target_path)
	func _process(delta):
	# Looking. Rotate _this_. Tilt _camera_.
	mouse_accumulator += last_mouse_delta # TODO: Cap the Y component.
	last_mouse_delta = Vector2() # Reset after we process the mouse so we don't accumulate between events.
	# Calculate our new position.
	var look_target = follow_target.global_transform.origin + Vector3(0, follow_height, 0)
	var target_position = look_target + \
	Vector3(cos(mouse_accumulator.x*mouse_sensitivity_x), sin(mouse_accumulator.y*mouse_sensitivity_y), sin(mouse_accumulator.x*mouse_sensitivity_x))*follow_distance
	self.look_at_from_position(target_position, look_target, Vector3(0, 1, 0))
	# For mouse handling:
	func _input(event):
	if event is InputEventMouseMotion:
	#event.position Will always be center when in capture mode. Same with event.speed.
	last_mouse_delta = event.relative

view raw CameraController.gd hosted with by GitHub

The player controller is fairly straightforward, so I’ve not included it as a separate gist. For a Kinematic Player, one can move relative to the camera direction like so:

extends KinematicBody

export var walk_speed:float = 5.0

func _process(delta):
	# Walking in the direction the camera is pointing.
	var camera = get_viewport().get_camera()
	var dy = int(Input.is_action_pressed("move_forward")) - int(Input.is_action_pressed("move_backward"))
	var dx = int(Input.is_action_pressed("move_left")) - int(Input.is_action_pressed("move_right"))
	var move = (camera.global_transform.basis.x * -dx) + (camera.global_transform.basis.z * -dy)
	move = Vector3(move.x, 0, move.z).normalized()  # Take out the 'looking down' component.
	self.move_and_slide(move*walk_speed)