First off I wanna say I really like the artwork haha.
I really really like this. One thing I must say is that it is very repetitive, and that's coming form someone who loves this type of music. At some instances it's very hard to hear the music evolve or add anything over time.
I feel like what this track is missing is just some random "One-Shots" going on throughout. Maybe every now and then just throw in a really reverberated snare, maybe some clicks panned slightly to a side, maybe some crazy vibrato - reverb synth. Just most stuff to listen to occasionally then just the one continuous melody, which is still really nice I must say. Vocals would be nice like you're suggesting.
What would make this track totally do it for me is if towards the end it got REALLY really big, with like an acoustic drum groove going on with wood blocks and stuff. I really like this though and I'm interested in how you take it!