A tool that shows the pathing of "walkers" before you place a building. 2. Gameplay Mechanics
Better heatmaps for crime, fire risk, or healthcare coverage.
If you are looking to code a feature (modding), you'll likely be working with C# (as the game is built in Unity). You would need to look into tools like BepInEx to inject your code into the game's assemblies.
Custom building projects with unique resource requirements.
A more dynamic trading system where prices fluctuate based on your exports. 3. Technical / Modding
A global labor pool toggle or more granular controls for industry priority.