How about make it so you can use a controller to play? It would be really good because I have a 60% keyboard with no arrow keys and i think that a lot of people would enjoy the game more if you could play with a controller.

Changing the game itself is probably not possible, considering the small space allowed. I don't know if it is possible to change the JS-code take in controller instead of keyboard buttons but I guess your best chance is something like JoyToKey (https://joytokey.net/en/).