Several things before I was even able to play the game:
1. I am always using Firefox, but after the game loaded to 100% nothing happened, like you wrote the "play" button didn't even show up;
2. Then several times I saw a notification that the game is slowing down the browser, so I had to close the tab to even be able to write this review;
3. I read the information about the controls: you should also enable a scheme for people that do not like the wad keys and prefer arrows keys controls;
4. About the medals: I assume that the further the game goes the more difficult the levels are becoming, so the points value of the medals should be different for different levels depending on their difficulty.
PS
The game finally loaded, but it lags horribly. Additionally the dolphin constantly gets stuck between the platforms or even inside the platforms.
BTW. Why am I able to shoot if the bullets are not killing any of the opponents?