City Bus Manager is a fun game and has a lot of potential, perhaps these are nice update suggestions for the game to add more challenge.

1. The possibility that you can place advertising on the buses and that this will give you extra small income.
2. New events such as having to make a temporary diversion on a bus line due to road works or an accident.
3. New event where a bus breaks down on the road and you have to send a mechanic to the scene, maybe add a small maintenance van or tow truck to the game? This may also bring added value to the mechanics.
4. Multiple types of weather conditions, for example rain and snow.
5. A better possibility to adjust the timetable during the day and evening. For example, in my city the city buses run 4 times an hour during the day because it is busier and in the evening 2 times an hour because it is less busy.
6. The ability to move the service center to another location on your site and determine which entrances are used by the buses without having open holes on the site.
7. Adjust the occupancy of the service center after office hours, such as the mechanics, cleaners and researchers.