The input time should be quicker, it sometimes takes a second or two just to change direction.
There should be a key binding to pick up dodge balls instead of just bumping into them.
The game is basically just a copy off of agar.io, but a different goal. Change the look of the game, maybe something like stick rpg style.
The game is way too easy. Instead of an open playing field, it should have rooms and corridors and things.
Finally, change the name to dodge.io instead of dodgeball.io, it's more catchy.