Stop Cheating in Simple Platform Shooter

I created a simple platform/shooter type game. One character shoots enemies coming in from either side of the screen at random.

I was thinking of adding in a high score list to my game, which would upload the result to an online table. I have gathered the concept of how to do this, but I have yet to implement it properly. My biggest fear is someone being able to create a bot, or something, which will be able to beat the game, destroying the high score table…how easy would it be to detect and stop something like this within the game code?

Detecting bots or macros would imply that you’re screening all input to ensure any superhuman activity is impossible. Then, if the speed and accuracy of this input exceeds the arbitrary threshold you establish for some length of time, you “know” the player is cheating. Unfortunately, determining this threshold is guesswork, since everyone’s reflexes are different: if it’s too strict you’ll detect your best legitimate players as cheaters.