JS exercise – UFO Shooter

Although JavaScript isn’t my main focus, during the course I’m participating at the moment, my attention got stolen by JS.
I’ve been challenged to write simple browser-based game. It is a shooter where a player need to destroy an UFO. 
Would you fancy to try it out? Here are some links:

the game: mkajzer.pl/ufo
github repo: github.com/mickaj/cl_kaczka