Simple idea: The UI shall indicate not only current idleness, but also "imminent idleness"!
Many games highlight idle builders. Telling me that my factories or engineers are running out of orders should happen before they actually run out of orders, because a lot of them can become idle simultaneously and/or I can't react right away because I'm putting out a fire somewhere else, leaving builders idle for quite some time. As a solution, the UI could display in a dedicated area on screen (as usual) and/or close to the unit itself an idleness indicator that is colored by "urgency". Suggestion:
- Red indicator: Currently idle
- Orange indicator: Will be idle in 10 seconds or less
- Yellow indicator: Will be idle in 30 seconds or less
... or something like that (configurable!). This should (more) conveniently allow keeping all factories and engineers busy at all times.
What do you think?