I am very keen about this new game. It will probably be very different than the first one, but from what I have seen, it will be sweet. A list of suggestions from my side. Maybe many of them might already be suggested before, but oh well...
Bus bays
The ability to build bus bays. These would allow the bus to stop without stopping the traffic behind the bus.
Toll
It is possible to build your own roads. Why not have the possibility to make toll gates or similar buildings to allow you to gain some profit from the roads and also make it more attractive to use publish transport instead of your own car.
Trolley Buses and normal buses
In CIM1, trolley buses are a replacement for the tram and they run completely separated from the normal buses. I think it would be a better idea to have buses and trolley buses under the same transport type. Trolley buses are obviously cleaner, so could be used for routes downtown, while normal buses are more useful for longer distances and residential areas. Trolley buses would also require overhead wires to be created, which will be an initial investment, but energy will probably be cheaper than fuel in the end.
Overhead wires / 3rd rail
The ability to choose from different types of power supply for metro's and trams. Building tracks with a 3rd rail would allow different vehicles to travel on the traject than tracks with overhead wires. So every vehicle would require either a 3rd rail or overhead wire to be able to traverse the traject, with some vehicles being able to use both supplies (3rd rail for underground, overhead wires for above ground maybe).
Customizing roads
The possibility to change roads that are already built: add lanes, change lanes to become bus lanes or make roads one direction. The same could hold for railway tracks. Maybe you want to upgrade a one-rail traject into a double rail traject so more trains can run on it.
I would also like to be able which lane will become buslane and on which lane the tram will run. Dedicated tramlanes would also be a great addition.
Terminal and Bus Stations
In CIM1 it is impossible to have a centralized transport system. In real cities I know, the public transport is usually centered around the train station, but this would lead to massive traffic jams in CIM, because there isn't really a nice way to build a bigger station. Busstations and terminal stations would be the solution. These stations could have a certain amount of platforms on which people can step into the vehicles. For trams and metro's, it could also allow a line to use multiple platforms, so when a vehicle occupies platform A, the next vehicle would go to platform B.
A to B lines
Lines in Cities in Motion have always been circular, but it would also be interesting to create a line that starts at depot A and stopt at depot B. There could then be another line from depot B to depot A. This could of course also achieved by creating a bigger circular line, but by using separate lines, it is easier to schedule your vehicles along the line (it would take ages for a vehicle to reach a stop at the end of the line, so there's a good chance the rush hour is already over when the fleet of vehicles finally reaches the end of the line). Combined with the previous idea. Lines could also be laid between two terminal stations instead of two depots.
Turning stations
Terminal stations should also allow trams (and metro's) to continue backwards, without using a turning loop. There could also be vehicles that have only one cab and need a turning loop to continue service.
More types of transport
I would like to see more types of transport: monorail, gondolas, etc. Maybe have the player choose X types of transport it can use in the beginning of the game, as some types of transport are more useful in certain scenario's than others.
More control over railways
Even while we have metro, we have no control over the "normal" railways whatsoever. I would like to see that the railway has more influence on the game. Ie people actually using the train to get to places. The player doesn't necessarily needs direct control over how trains run, but I think it should be part of the whole transit system.
The same holds for airports btw, as that is a place where many people "enter" the city.
Ferries
CIM1 had water boats, which were in most cases not that useful. Maybe add the possibility to have ferries which allow cars and buses to enter the ferry to be shipped to the other side. This could be a cheaper alternative for bridges.
Special traffic lights for buses/trams
In the city where I live, buses and trams have special traffic lights that give them priority over other vehicles to keep them on schedule and make the move faster through busier areas of the city. It would be nice to have this option in CIM2.
Line numbers/destination signs
Not really useful maybe, but if you want to make a model of a real city or if you have specific plans in the sandbox mode, it could be a nice addition.
Line variations
The ability to ignore stops during a certain time period. Maybe the buses don't drive on to the suburbs in the middle of the night, but stop at the edge of the city. Or maybe during rush hour, the bus skips certain stops to make it move faster. In the city where I live, there is a bus line that goes let's say like A->B->C->D->E. During rush hour, it skips stops B and C (so it becomes A->D->E) while another bus that only drives during rush hour follows the route A->B->C->D.
Track maintenance
Vehicles need maintenance, but so do tracks. Maybe lines need to follow a reduced service or close down for a certain time period to allow track maintenance. (Building or upgrading tracks could also require more time).
Advanced yards
It could be really beneficial to have the emplacement before a big station with a lot of lines being build in a smart way to have at little crossing lines as possible. In CIM1, if 2 lines enter a metro station from the same site, they would always coincide resulting in delays.
It's a really long list and I hope to find some of these functions in the final product. I am really excited about the game and looking forward to more gameplay material.
as discusses already quite heavily, you won't get completely realistic simulation, so i don't think that this should be a reason to prevent the system of using the front door only for boarding. But in general, i really don't care how the doors are used in the game...for me the best would be if i could decide what system to use by the line and maybe time of the day (so that on busier lines i'd need inspectors, which makes operation more expensive but faster or entering only at the front door, thus reducing costs for that line).
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