In response to your suggestions in subject of puzzle connections, which was not so intuitive and hard to understand we've added road connections points on puzzles, they will help you to understand how road connection mechanic works.
And the rule goes: Two puzzles will connect into one road only if one of its connection points will overlap each other and will face the same direction.
Other changes:
1. Fixed an issue where scrolling through puzzle selection would sometimes not fully scroll blocking half of the first and the last puzzle on the list.
2. Corrected names of start and end points in third tutorial.
3. Added the ability to reduce the number of the traffic light sequence with the right mouse button.
4. Added the ability to pick up a built element with a shortcut (ctrl + x).
5. Added the ability to copy selected elements with a shortcut (ctrl + c).
6. Removed an invisible blockage in the level editor that blocked the detection of a mouse click on the left edge of the screen.
7. Fixed an issue where start and destination points didn't display names on mouse hover in tutorial levels.