Alright, so I'm pretty sure the answer to this question is so obvious that I'll be looking back on it with shame in half a year, but I'm brand new to Construct 2, and this issue have been troubling me for the past 30 minutes at least.
To cut to the chase:
I've tried re-making the finished game that you can download at the end of the "ghostshooter" tutorial (the one titled: "Beginner's guide to Construct 2"), in my own project file. However, this is how the game I made looks like when run in a browser (notice: I followed, as far as I am concerned, every single step of the tutorial):
But this is how the ghostshooter file as downloaded by the end of the tutorial looks like:
So, as you can see, my game takes up most of the screen (1920x1080 screen), whereas the tutorial file only takes up a way smaller portion of the screen. How can this be? I've done my best to match every single setting in the tutorial file.
Also: Is there any way to make large images on forum posts show up correctly? Most forums have a [spoiler] feature. Doesn't the Construct 2 forum have this?