It's a pretty good start. I'm intrigued. Shame there's only the tutorial done. The music and ambience in the trailer and the lead-in credits to the title screen do a lot of the heavy lifting for setting the tone. Might be putting the cart before the horse a little bit to polish the title screen before there's any gameplay to test out, but I'm assuming you've got more in the works that just didn't make it into the demo. 

The simple visual style works well and acts as a good cover for the deceptively good sound design. You could do a lot with this. I look forward to seeing where this goes.