I know dovetails is working on trying to implement a manuel firing system for steam locomotives. Some features I like to suggest to add immersion to help make feel like a real steam loco are like hissing steam coming from the pistons while the engine is in motion. Have the player oil the pistons before the start of each service. Have water over flow from the tender when filing the tender with water. The last one is to get the ai fireman to shovel coal into the firebox.
Working steam heat with leakage from the pipes and venting under the coaches when switched on would be a nice touch, too.
