I'm going to focus not on little glitches that can be ironed out piecemeal (by which I mean just about anything in the graphics or user interface), nor things that simply haven't been modelled (yet), or anything like that - but on things which are in the simulator, and are done wrong, and are so wrong that it interferes with the railway experience.
There are two major areas that are this wrong: the Physics and the Signalling. Both of these suffer from fundamental design flaws which, so far as I can tell, date back to MSTS1 and are therefore an entire decade old.
That's not to say that they haven't been improved since then, but that they are so badly flawed that incremental improvements will not be enough to win the respect of the community. I believe they have to be replaced, and so this post is a guide to RailWorks' developers on How To Do It Right.
Let's start with the easier part: The Signalling.
The job of any signalling system is to stop trains running into each other by accident. It accomplishes this enormously important task by communicating limits of movement authority to drivers. Signals are not merely points indicators, or repeaters for track circuits, or even under the exclusive control of a single signalman. Yet RailWorks often treats signals as any of these, and exhibits behaviour that would be fundamentally and dangerously impossible on a real railway.
The result is that signals are seen to fail, sticking on red permanently. They turn red against the player under normal traffic conditions. And yet they can let AI trains enter the player's path under fairly repeatable conditions. All because the signals are set up in a fundamentally backwards way.
Allow me to describe how real signalling is done.
The first step is the Working Timetable. This describes, often to halves or quarters of a minute, where trains are supposed to be, when they're supposed to get there, and when they are supposed to leave to get to the next place on time. It can be (and often is) amended on a daily basis, and extra trains can be inserted at rather short notice, but it means that each signalman has a pretty good idea of where each train should be sent, and when.
But the Working Timetable is only advisory. Signalmens' first priority is safety - timekeeping comes a distant second.
When a train approaches a signalman's section, at first it does not have authority to proceed through it. Therefore, the section signal (often called Outer Home in British practice) will be kept at Danger, and any preceding signals will be limited in their displayable aspects by that.
Next, the signalman decides what route to send the incoming train on within his section. This might be into a station platform, across a junction, to the edge of a yard, or straight through. It must not occupy the same space as another set route - and the signalman must take crossings, points, and any other fouling considerations into account. (In UK practice, this also means leaving an "overlap" beyond the limiting signal clear of traffic until the train has been brought to a stand at that signal - but that's a detail.) Once determined, the route is set using points. It is then possible to give a train authority to use it, which is done by setting signals.
But once decided, this decision can be changed - unless it has been committed by giving the train authority to proceed along it. The only way to retract that authority is to reset the signal, wait for the train to stop, and then wait a further two minutes to ensure the driver has not internalised the previous aspect. Only then can the route be unset.
Modern signalboxes contain interlocks which enforce the above rules quite strictly - indeed, the signalman might only normally need to input routes and keep an eye out for emergencies, with a computer actually setting points and signals. Older boxes may only enforce some of the rules, but interlocks between routes and signals have been standard practice since the mid-to-late 19th century, and may lack only the timer on the release. Train presence detection and interlocking is a newer technology, only becoming properly robust and widespread in the mid-20th century. With these older boxes, the signalman was responsible for enforcing the rules himself - rules which had been developed through long and bitter experience.
Note that an "authority of movement" is given implicitly for "automatic" signals. Automatic signals are only used on "plain line" sections - with no points or junctions. The implication is that if a train has entered the section (always under control of a signalman), it has authority to proceed to the other end of it, provided only that other trains have cleared the line ahead. This is the major difference between automatic and controlled signals. A "semi-automatic" signal is one that is normally automatic, but to cope with unusual situations is capable of being controlled - in this case it is given a "standing authority", which can be revoked by the signalman using a procedure and a control line.
Main signals convey authority of movement towards the next main signal or buffer stop (which counts as a permanent Danger signal), along the set route (which, remember, never changes while the signal is showing "proceed" or the train is still in section). Some types of signal are capable of indicating which route is set, while others only indicate if a restricted speed is required. Most are capable of showing whether more than one of the sections ahead are clear - and unless an emergency arises, this authority is never reduced.
Distant signals are simply main signals which cannot show a Stop aspect. But in British practice they have a subtlety - they indicate whether any of the signals between itself and the next Distant signal are at Danger. In modern practice, Distant signals (or main signals capable of showing a Caution aspect) are placed frequently enough that this situation never arises.
By the way, the two-aspect colour light signals in British practice are only used as direct replacements for semaphore installations, due to the limited information they can convey. They have absolutely no place on the approaches to Paddington!
Finally, shunting signals operate on the same principles as main signals, with two major differences: they do not guarantee that the track is unoccupied, and they provide movement authority only to the next shunting signal, the next main signal, the next obstacle, or the limit of shunt, whichever comes first. They are not point indicators, though they are usually interlocked with the points to guarantee that a route has been set. The fact that they may be operated from a ground-frame by a shunter (who may be the train's guard or fireman in practice), instead of from a signalbox by a signalman, does not change their fundamental function as movement authority indicators.
At this point I would like to point out that a UK-pattern shunting signal shows either a red/white aspect or a red/red when at Danger (depending on it's age). The type which extinguishes when not giving authority is only found attached to main signals, and is called a "calling on" signal, with the same semantics as a shunting signal.
At any given time, a train is either under main-signal authority or shunting-signal authority. It is not allowed to change from one to the other without first exhausting the existing authority. This may be done by bringing the train (nearly?) to a stand at a main signal at Danger, then using the calling-on signal on the main signal post to transfer to shunting authority. Alternatively, a train at a stand may be signalled to reverse by a normal shunting signal. A transfer back to main-signal authority is simpler - the previous shunting signal gives authority to the main signal but no further.
Approach-Release signals are a bit special. They effectively withhold movement authority until the train has been shown to be travelling sufficiently slowly to traverse the junction safely. They are only used when the speed limit for a diverging line is substantially lower than for the straight line - the classic example is a 90mph main line with a 25mph crossover. For less severe examples, such as if the line speed is 50 or 60mph, the Caution aspect would be used instead of the Stop aspect - this is simply witholding the authority from the signal after the junction, and is rather preferable from the driver's point of view as it is more predictable.
The non-obvious point is that the authority is released by a timer (assuming the signalman has given his authority) which is triggered by the train entering the section. A good driver knows this, and will brake early so that he is travelling at the correct speed when the signal clears, but still with enough braking distance to come to a complete stop if required. A poor driver who only brakes to stop at the signal would have traversed the early part of the section too quickly, and will have to come nearly to a stop before being able to restart. The real point is that the position of the train is not always the same when the signal is released.
Fundamental principles:
A signal gives authority of movement over one or more sections of track beyond it. Until that authority is given, the signal displays Danger, or the nearest available to it.
The aspects any signal can display depend on the aspect actually displayed by the signal immediately after it on the set route. This is of course recursive.
Whenever a signal is showing a proceed aspect, the set route as far as the authority of movement that it conveys is locked down and cannot be removed or interfered with.
Main, distant and shunting signals are fundamentally the same. They differ only in the quantity and quality of authority given.
Approach-Release signals (of both Stop and Caution types) are implemented with a timer, not a position sensor.
My Physics rant follows in a separate post. Please leave the thread clear for it...
