Since I'm going to be doing a lot of commented reviews, I'll keep it well structured by supplying you a reason with each of my ratings.
Game Design - 3 Stars - The game design was pretty simple and the game was very short so I wouldn't call it spectacular but I wouldn't call it bad either. It's average and simple.
Fun - 4 Stars - I did have a decent bit of fun breaking everything and shooting at that big dude at the end but the reason it didn't earn 5 stars is because I could only shoot at each thing once. If you made it so the props kept dismantling into smaller and smaller pieces as I shot them, it would've earned 5 stars in this category.
Innovation - 4 Stars - I was thinking about putting 3 stars here since your take on the theme was very simple and somewhat literal but when I got the boss area, I definitely felt like "ok this is exciting looking" so I decided to bump it up to 4 stars.
Theme - 4 Stars - Once again, I was going to put 3 stars here but your boss fight was definitely an interesting/unique take and so I decided this category should get 4 stars as well.
Graphics - 3 Stars - Graphics aren't bad but they aren't great. They're very simplistic and I can tell your gun was just the default one offered with the Unreal Engine. I don't know if you drew that little goblin but he's pretty well-drawn. I liked him!
Audio - 4 Stars - I like the sound you used for the gun and the music was short and simple but it fit the setting pretty well.
Unfortunately, I wouldn't consider this game for top 10 if I was a judge BUT it's a nice little demo game to show off your skills with and I would NOT call it a waste of time since I did get a few minutes of fun out of it. Good job!