For anyone wondering about "Error: Could not embed this media" it's because the game author needs to export this project as HTML5 and has not done so. And really there's no excuse for not doing so and hasn't been any excuse for quite a while now.
If your browser has UnityWebPlayer you'll be able to play the game and if it doesn't you'll get that error message above. But literally all the author would need to do is open up Unity again, and this time export to HTML5 format which Unity even allows you to do! And then it would work in the vast majority of browsers instead of just Internet Explorer on Windows or whatever.
So I think a no stars rating in these cases is fair considering they've had literally years to do this and can be done in less than 5 minutes if they'd just stop being lazy and do it. Trivial fix.
Plus most Unity game authors have already done this so as you'll notice no problems with their games and they just work, unlike this or other games still stuck in the past requiring UnityWebPlayer plugin support, which isn't even available for most OSes and even on Windows isn't available for most browsers, and even sometimes doesn't work in the few cases it is available on a browser in Windows (many people could never get the thing to work!)
I'm sure it's otherwise a great game, but yes there is really no excuse for this!