The game works on pretty much any emulator online. The problem is there's no way to shoot at any of the targets on the screen, whether they be the ducks or the clay pigeons. I've tried every button on my keyboard that matches the original controllers buttons...and not one of them shoots the zapper. I've even clicked the left mouse button and that failed to work. It's a great game. I just can't play it because there's no online emulator for the zapper.
And, ever since Java got replaced with something new, there's not even a 2-player option to play other games. Every game I can play now, I can only do so with one player. I have to avoid any game that requires two players since that option no longer exists. And, unless an online emulator for the zapper exists somewhere, it looks like I'll also have to avoid Duck Hunt. That's a shame because this is one of those REALLY great games I remember playing when I was a kid.