Currently it’s really hard to know which stations are upgraded and which aren’t, and just as hard to click through each one and know you’ve hit them all. On top of that, I’d say it’s too difficult for a layman to remember which research upgrades apply to each station. My suggestion is to:
- Add a way to cycle quickly between all stations (brackets, carrots or some other binary keybinding)
- Add UI after each research category is completed that points out which production station it applies to, and
- After a research category is upgraded, add a button to upgrade all applicable stations
Long-term it might be worth looking into a way to easily view which stations are fully upgraded, though that seems like a pretty hard UI challenge. Maybe some kind of station “rating” when you’re at max zoom. (i.e. the way that Cities Skylines has a visual “bar” rating to show how upgraded a building is, like 2/5 bars.) Seems like that would be fairly cluttered though.
How about an office research option that you can just build. When clicking on the office you get a list of all stations in the factory with a small schematic overview window. When you select a station from the list it will be highlighted on the schematic overview. Also behind the stations in the list is an easy overview of the upgrades with an option to enable/disable them from there.
What about a screen like a spreadsheet, Listing your Slots, with buttons to click, check, to apply the upgrades, that you can access when you like, but also, when the research complete window pops up and says upgrade / update cars. Also, if when that popup happens, it would stay up so you could upgrade the vehicles, and then the slots, and then choose the next research.
There now is a button to upgrade all applicable stations, but it is still very easy to forget to update future stations. I suggest there should be two buttons, one to upgrade all applicable stations, and one to upgrade all applicable stations and make the update default in future stations of this sort
I re-built parts of my factory, and it took me a long time to figure out that some of my stations did not have the necessary upgrades to fit the cars as I needed.