Oh I just played that one myself too haha
That game was a bit on the louder side, but not *that* loud for me. I don't have to turn down the volume of my browser to play it, and YouTube videos or such aren't drowned out by it either, so I'm not sure. Different settings for different hardware/software for different people I guess, could be a lot of things. That's probably why we didn't catch the loudness ourselves until it was too late, I suppose.
I think the general thing to have learned here is that volume sliders are a must!