This is what the topic says for it - After your game is officially over, take a screenshot of your score and comment below with said screenshot. This is how you enter into this challenge. I will take your highest score -aka the total of three runs - as your entry.
You wrote it out nice and clear - Highest score will taken as the entry.
I'm not going to respond to your implications that I cheated in this challenge, because that would see me banned. I'll leave that response to your imagination.
But now that I think about it, a number of entries have had their dates cropped out. So if you're going to say that their was no way to prove that the score was achieved during the challenge time, you also have to disregard the entries that do not show dates.