Okay. This game is terribly broken. Where to begin?
Hit detection is way off. Also the sheep just flat-out stop coming at some point (tried in both Firefox and Chrome), and you only score when you hit a sheep and die and your score is recorded, making the two score medals very trollish.
Two-player mode is terrible as for some reason WASD controls the guy on the right while arrows control the guy on the left -- backwards.
For anyone wanting those elusive troll medals, get the score you need (either 1000 or 3000) points respectively) and, of course by that time there'll be no more sheep, so how do you end game and claim your medals since pausing and returning to menu doesn't award it? What you have to do is right-click and click Forward. I don't think there's any other legit way to obtain them in this broken game.