Yes, headphones are recommended, especially as the music contributes a lot to the ambience of the game...which reminds me of another game that uses headphones...or should I say is almost entirely dependent on them? And that game is Papa Sangre. It seems to have disappeared in the mists of time. It would be good if they did a sale to generate some interest given the way it just disappeared from the App charts.
It's a nice idea, but it's so "off the beaten path" that most folks will simply not slow down and give it a fair chance. Yeah... I'm one of them. I simply can't care enough to reach for my headphone and plug 'em in. Especially with an iPad.
Bought this a few years ago. Never dared to install it again on my new shiny iPad Air 2 on iOS 9 as this app hasn't been updated in quite some time. Tempted though. This is a very nice game!