Hi Humane Tiger,
Thanks for the feedback. Very happy to see that art is appreciated !
I'll take care about SFX and BG music in one of the next updates.
I totally agree with the need of a good tutorial, and it's very important to propose a smooth learning curve.
I usually start with kind of Story mode, where it's easy to ramp-up with some kind of demo-gameplay with story around, before serious business starts. Here, with Endless mode as first feature, I definitely need to find the appropriate way to teach features.