You can delete a mission you have already succesfully completed. It is often nice to solve the mission again, perhaps in a different way.
This was made after user feedback.
Significant quality and technical update August 11th
Quality and technical update includes
More voice acting
More player guiding
Improvements of lightning
More events and missions
Update July 22nd
Tiny improvements after customer feedback like slightly less police on the streets and more things to move or throw around. Some more sounds and more lights to school scene as in this picture.
Update July 17th
The City map has been updated so that the green guide pillar is also visible on the maps.
Update July 13th
Objects are easier to move or even throw around. Some more sounds.