Then there is probably an issue with your keyboard not wanting to register multiple keypresses. you can try using a combo of arrow keys and wasd which usually should work
I have had this issue with other games on itch before but I thought it was a feature being only able to register two keys btw I have some free music that will go great for this game you have permission to use it put this into google https://flat.io/score/5fe4c88ce5a7845e77f62981-game-music-1?sharingKey=6a1b81239...