Hit particle velocity is bound to amount of aliens on-screen

[ironkayman]

This presumably is caused by the fact that every alien calls an update() mathod in their designated object on a sprite list of particles, which is shared across all active (not reaped by emiter) Alien instances so as a result we get multiple update calls per frame.

[ironkayman]

May be considered a feature, while the repeaded updates may cause performance issues in a long run, currently this behavior my be favorable since it fits to a more active gameplay due to more enemies present onscreen, creating more in-action effect.