Okay, but please pay attention where you post.

GUI

increase play window

remove settings word, the gear icon is enough

fix the colored font, it's unreadable. A small 1-2px black outline might work, with slight increasing the font

GUX

unable to buy button, should have some sound failure horn.

WASD+Arrow keys+Mobile, to work simuntaneously

Game pause via key, is always helpful

your plane should have some sound, or at least smoke effects line as he flies

timer should be top, not distractive as is now

There are lots of other things to comment, or improve. Destroying planes with rockets, might be fun for boosting the score, while speakign of it, what is the purpose of your game? Is it plane challenges? If so, the name and style in playing, should be towards hinting that. Remember, challenges don't like forever, so you might want to tweak your logic. Otherwise it's a simple evader with minimal effects.

How long you made this game, and what engine? It looks the top pause bar recognizable to me..

Good luck!