Here's some feedback:
1. The theme
I like the idea of the game. It's a different take on the breakout game, but to fit the theme maybe make an object that you have to protect.
2. The gameplay
The game is also fun, but i noticed that you can just press all the keys at once and will always win. Maybe implement that when you press the wrong key, you lose.
3. The graphics
There are some easy things you can do to instantly improve your graphics: Choose a nice font on websites like Google Fonts and replace all your text with it. Then go to a website like Coolors.co and choose a nice color scheme,especially change the background color (if you don't know how to, got to main camera and there select the right color).
4. The sound
Add some sound!
I hope my feedback helped you a bit and if you have some time it would be nice if you could check out my game too. Thanks! :)