Good work for one day
Good work if this was your first and you made it in a day, but honestly it's pretty boring. You could try adding some sound effects and background music in to make it more interesting. I'm sure there are plenty of suitable sound effects free to use online but i cant remember any sites right now. I actually really liked the background art how it has a sketch book look to it, but adding some colors in would really make it stand out and give more of an environment to play in. Possibly have a simple plane or two fly by every now and then, maybe for bonus points. Better animations would be nice too. If you're really interested into making this a full-fledged game you could add a simple targeting system with the mouse. Progressing to boss battles, different weapons, and a menu system would really make this game stand out. But this is all if you want to invest a lot of time to make a large game. If you just want to keep it simple I would say just color it up a bit and add some sounds for a big improvement and never forget the credits. Have fun with your future submissions.