You can define an actor to that he must be in contact with it to be there, or the invisible wall will work as well. you can go either way. In the dragonfire scenario I use invisible barriers on the bridge just over the entrances and in the treasure room.

I was trying to make it fire randomly like a pile of ordnance burning in the turret, but sometimes it just makes a spray upwards that make it more dangerous than an active turret. I will try to fix that next, it will still shoot random bullets when burning, but at a much reduced frequency, or maybe that a turret can only throw off at most 2 random bullets while on fire.

I think it has something to do with the fact that there may be spaces in the scenario name. I think you have to modify the jar name in some way, but I am not 100 % sure.

when you share the scenario there is a check box at the bottom that says "Publish Source Code" check that box and an open in greenfoot button will appear on this page.

That did it. Check the ScoreBox class, I load a file called Overwrite.ttf to make use of custom font. Check project for location of Overwrite.ttf