It’s possible for using developer mode to cause save corruption and game crashes. Its alternatives are not all reversible. Regular backups are highly advised.
There is a developer menu in Cities: Skylines II that allows you to modify the game.
Enabling Developer Mode
- Right-click the game, open Properties
- Add -developerMode to the Launch Options at the bottom
Using Developer Mode (Cheats)
Once enabled, the developer menu is opened by pressing Tab. The Simulation tab contains various cheats such as instant zone development, disabling pollution, or disabling the need for services. Spawning events and disasters requires selecting a building beforehand.
Checking “bypass validation results” disables checks before placing buildings and networks and can be used to create quays easier closer to the waterline.
The add object menu is opened by pressing Home. It lets you access many more objects than those available through the default user interface. Adding moving objects like cars or cims is likely to cause problems.
Developer mode video tutorial:
The developer menu: