Make the user reset, not regret.
Today I wanted to stop the user from accidentally resetting his solution, since I noticed players would sometimes do so. In my first iteration, I would have a normal menu like popup. But that seemed very intrusive.
So I came up with the idea of adding a little animation to the button, that shows the user a “red button of kaboom”.

Other animations.
afterwards I was working on the animation to clarify a train cannot leave the level without missing his goal. Since there is a potentially large number of stations, that fulfill a request along the list of requests, I added checkmarks to the stations that are ok. But then it gets a little bad. How to show, that there is no other way from the last possible and desired step? I am still not sure, but I will see, what I can do..