For White...

world.gd

extends Node2D

const BLOCKS... # Copy/paste all blocks here

var blocks_array = [BLOCKS_TYPE_I, ...] # Add them all into this array

@onready var block_spawner = $BlockSpawner
@onready var safe_zone = $SafeZone

var spawn_countdown := 0.0

const SPAWN_COUNTDOWN = 0.1

func _ready() -> void:
  spawn_block()
  
func _process(delta) -> void:
  if Things.has_fallen:
    spawn_countdown += delta
    if spawn_countdown > SPAWN_COUNTDOWN:
      spawn_block()
      spawn_countdown = 0.0
  else:
    spawn_countdown = 0.0
  
func spawn_block() -> void:
  var random_block = blocks_array.pick_random().instantiate()
  get_tree().current_scene.add_child(random_block)
  random_block.global_position = block_spawner.global_position