Your description says to download the exe instead of the webbuild, but as its still up and I'm not on Windows I use the webbuild anyway. The idea is nice, though shooting through to the core of any planet (at least on the first dozen) is no problem and I'm not sure what I need turrets or upgrades for. The apparent lack of music is a bummer, especially as there is a music volume button (at least I suppose that's what it is).
The idea is pretty nice, if there was more of a challenge added to the game this could be real fun. As of now, it feels somewhat unfinished, though I have to give you the benefit of doubt here due to the downloadable release :)
Also, something is wrong with the project settings as the game opens in a new window with wrong sizing.
All of this may be fixed in the downloadable version, but I recommend to update the webbuild to your final version or removing it (losing some players then, probably)