Ragdoll physics are procedurally generated animations to mimic a freely moving body and usually is concerned with the death of a character or after their death. It is used in place of the more traditional pre-animated deaths, the benefit being relatively more realistic body movement during and after death and animation appropriate to the surroundings and condition of the object (locations such as stairs or cliffs benefit the most). Occasionally, methods that combine ragdoll and traditional death animations are used to create a blended ragdoll animation. This allows the animator to give a more realistic death animation, simulating the actions of a character as he or she dies, while still constraining this motion to the game's physics (preventing clipping). One of the first games with this feature was Jurassic Park: Trespasser. The assimilation of ragdoll physics was greatly contributed to by the development of the Havok Physics engine and commonly associated with Valve games such as Counter Strike.