A few thoughts after checking out your game...
I like the core mechanic a lot. Angry Birds with a speed element to amp up the pressure.
I like the game loop as well: battle, upgrade/repair. Very clean, at least at the beginning.
I wasn't very good at it, and I worry the difficulty ramps up too quickly. I lost the third battle. It's probably a nice recovery mechanism that after losing it I got four coins (only having gotten two for winning the second battle) but it wasn't enough to motivate me to continue. Had I won the third battle, I probably would have continued at least a little further in.
The control itself is excellent (and made for mobile, I think, though I played on mouse on phone) but I think you can do more with color scheme to show where the arrows are going. It took me way too long to notice the relationship between the lines I drew with my mouse and the cone of impact below. I wonder if you can't add an effect to the cone so it's more obvious earlier.
I didn't stick around long enough to really learn how deep the game goes, but it taught itself well without a burdensome tutorial, and it was genuinely fun and exciting. Just a bit too hard for a goof like me.