The Trespasser engine is one of the most unique engines ever coded. It was the first engine to realize and implement an actual physics engine from its conception, and thus allow the game worlds to operate under actual physics rules. It also provided a realistic sound system and utilized complex AI algorithms which powered the dinosaurs. However, for all these fantastic firsts, the engine is not without its constraints.
The Physical WorldEdit
The Trespasser team set out to create a game that truly mimicked the real world. They perceived a game which was ultra-realistic. And in retrospect, many of the goals they set for themselves were met.
Ammunition counting is handled by Anne using such phrases as: "Feels Full" and "Almost gone" and "That's it."
The player interfaces with the world by controlling and manipulating Anne's arm and hand. Players need to bend down, extend the arm out, and grasp objects to pick them up. In addition, firearms must be sighted by actually aligning the sights by moving Anne's wrist. This method of interface is often found to be clumsy by inexperienced newcomers, and led to low ratings from reviewers, even to the point of calling Trespasser an "Arm Simulator."
Everything in Trespasser behaves according to the laws of physics. Each object is assigned a set of properties which dictate how that object responds to external stimuli.
Unlike 2's solid-state physics, Trespasser uses a "Box System" to depict physical interactions. Under this system, every object behaves as if it is encased inside an invisible box. Trespasser uses what is known as the Penalty Force Method for collision detection, whereby if two objects come in contact with each other, they push away until their invisible boxes are not longer touching.
By far what sets Trespasser apart from even other games of today is its sound system. The developers called it "Real-Time Foley"; the engine can produce in real-time a sound for any two objects colliding, taking into account distance and speed. This is achieved by dynamically mixing several sound effects together on-the-fly.
The original Trespasser levels do not contain animations in the tradition sense, although a system for keyframing objects exists.