Create your FPS on Rails as classic Arcade games as Operation Wolf.
Thank you Facecrime, sorry I am not sure to understand well the jitter thing. You mean that the image is shaking when you zoom?
On rails is any movement of the camera that is not controlled by the player directly. It can be forward, on a side, in vertical. It doesn't really matter. The first on rails game were 2d as this and just moving on a side. The most famous Operation Wolf.
The options 1 (Bullet Behavior) & 3 (Pathfinding) are the real on rail movement, while the 0 & 2 are controlled by the player and even if not on Rails I thought it was nice to add more variety to the Template.