The message I received when playing the game was "Failed to load JavaScript code used in events. Check all your JavaScript code has valid syntax."
Since then I have programmed the game myself and it works fine. Although I have noticed that Construct 3 is a bit unstable, it has bugs. Often when I run script it just loads a black screen then ill close the window and run it again and it works also another thing i noticed when programming the beginner tutorial game it instructs me to put the bullet and explosion off the edge of the layout and that will occasionally throw an error so if I move the bullet and the explosion onto the layout the game will run, other times the game will run with the bullet and explosion off the layout.
So I'm guessing something simple like the bullet and explosion issue is causing the problem in the demonstration game but I really couldn't be bothered having a look since it only takes about 20 minutes to put the game together myself.
But apart from the little things Construct is great very easy and understandable to develop games in, I was trying out GameMaker Studio before this which is good but I think Construct is better, I,m probably going to purchase Construct for my future projects after I get more familiar with it.