FF::Scn::BoidRules.add(
  FF::Sys.new('DecaySpeed', priority: 50) do
    FF::Cmp::DecaySpeed.each do |decay|
      boid = decay.entities[0].components[FF::Cmp::Boid][0]
      boid.vx *= decay.strength
      boid.vy *= decay.strength
    end
  end
)