TL;DR
A subtle change that would make map edges more appealing. A "skybox" of sorts.What?
I propose that instead of the very sharp cut-off on the tutorial maps as shown here:![Image](https://forums.factorio.com/images/ext/92a678e0e656fb482b52162fc7532a8b.jpg)
Something like this is implemented:
![Image](https://forums.factorio.com/images/ext/c499c166d382fc4e8e385d0ff6ecb75b.jpg)
Not the best example, since using the cliff texture would give the impression that it could be bombed. A different mountain texture could be created for better effect. It could fade out into black as shown in the mock-up or it could be an endless loop of un-walkable looking terrain.