Improvements to do: for the failed attack (and the attack cooldown that follow), make the game check if any enemy as been killed at the end of the attack, not during it. I have often got the failed attack while I did get the robot.
Attacks also damage robot below you if you fall on them. Since the game is a runner and jump, you will inevitably fall on the robot, especially since they often appear near the edge. As of now, you have no way to avoid these damage (the simplest way to do that: the player is invincible and destroy robots on touch during attack. The cooldown when you miss will make attack spamming a bad idea)