Gave it a try now and beat the game as it is now (1 level only).
First of all, there isnt anything critically wrong with this game, but it is basically already good as it is. Only that it can be improved further.
There is some confusion with learning the game, but eventually, and quite fast too, you do learn almost everything. There were only very few things I didnt figure out in the game, basically at all, but they werent that essential.
For example, in version update it mentioned that 40 percent of empty boxes are empty, and 60 percent filled. I didnt realise this until I read that version update text. So that doesnt translate in the game. Perhaps add a sound or short animation showing that box was empty.
Perhaps this alone added to the confusion that I am stil not sure what all those boxes too, but maybe point is that regular boxes were random, and others were actually set, as in similar looking box (at least the mine box) would always contain the same thing.
Mines had double problem. First one was that there was no option to choose the keyboard buttons myself. I am using Advantage 2 keyboard, which means that to use wasd and "space" at same time, I need two hands. Since my other hand is using mouse in the game, and other game is using wasd, I had to use my third hand for the space, which was difficult, and hence I didnt actually use mines, except to give them a bit of test. And that test seemed like those mines didnt do anything. Small guys, big boss, they all walked to mines, mines disappeared, but didnt seem to do anything. A bug or did I not understand them?
To get replayability for a game like this, is basically to ask for email and have a highscore list, so repeat play is to get hirher in the list against other players, so in that sense your registration demand is understandable, for to take myself as an example. I had a lot of fun playing this game for this short while, but I see no reason to return to play it ever again, especially since I am not one of those who usually is interested in competing against high score.
In addition, right now there is only this one level, so instead of having endless mode, there actually is no fun in competing against the high score either, since right now climbing on the list means you just keep playing the same again and again, and it is not a matter of if you are more skillful than others, but whether you are willing to waste more time of your life to this.
As I am not much of a fan of this short game genre, or, endless game highscore type of games, I am not able to say how this should exactly work, that should you just add endless mode here or what. To get me to play this more, would be to add for example a map with locations that you need to beat, and when you click on one of these places, then this kind of battle starts, and you get upgrades etc. I could easily see myself spending some time with a game like that, since this was quite much fun.
Especially the shooting was very satisfying and fun. Other player pointed out that it is getting bit annoying repeatedly clicking mouse, and I agree that it is so, I too fel bit annoyed continually clickin, especially since for last couple of years my hand have started giving me trouble doing so, as in I sometimes get pain to my fingers rapidly clicking for long time.
However, that said, while I would quickly think it would be nice to have option just keep mouse button down and it keep shooting, or auto-shooting even, I however think the game would lose something changing it away from clicking. I dont think the game would be as fun anymore if there wouldnt be the clicking included.
But having some break from continous clicking would be good, so maybe an option to sometimes have machine gun for a while, which would work by simply keeping mouse button time, until clip is empty, at which point it goes back to regular clicking. That could work as giving break from clicking, and yet not ruining the game completely.
Gane ending was bit confusin. Couple of first times when I died, I wasnt sure if there was some chance that I actually wouldnt be dieing. It always felt like I died twice basically, and that the second death could have been avoidable, especially due to name of the title.
Similarly having to click right mouse button at end of game was bit strange feeling too, but nothing critical again.
And the meny navigation had similarly slightly clumsy feel. As example, moving mouse to left-top revelaed the keyboard/joypad control, but it seems you didnt have way to get it to move back to its position, but you had to make some selection, which meant that if you just checked, you had to click twice the same setting to have just watched what it looked like there without doing anything.
Moving out of top of the appearing menu, had felt natural way for it to close again.
Similarly going to shop and having to click that small shop-icon again wasnt most natural feeling either. Would have liked there to be big red X somewhere to click, making it feel more natural and not needing to feel slightly unfcomfortable. Nothing critical, just that could be improved. As I said, things work already, just that game gets slightly better when things work smoother.
Big Bosses attack didnt translate very well to the player. I never felt like I understood its attack. I mean, I understand he is just leaping towards you, but I dont quite feel if there is limit to his leap distance or something like that. It felt more like sprite just moves towards me in some way, rather than big boss actually making an attack against me.
Except for some slight confusion, things in this game are quite well done to be clear. Like you can see the shooting distance, although, that was something I would have liked to be able to affect. Like start with small circle, then upgrade it to wider distance. That had been lot of fun, now it only served as making clear the distance you can shoot at, instead of being able to affect the distance too.
All in all, very fun short game, which I hope you will make a longer one, or then at least remove the registration, since in its current form the forced registration surves no purpose but to avoid people playing it. However, adding endless mode would already give enough purpose for the registration.
Although I had a lot of fun, and extra points from having even a plot with animation explaining it, and entro too, I dont think I will be playing this game again every again, since there isnt anything that appeals to me personally, that would make me come back, but dont take that negatively, since I am simply not the target audience.
I dont usually play endless games, and like you had skins there (good idea) they have no use to me. While I of course understand that people like to have different skins, I personally dont understand the appeal of skins. I would however had liked if in addition to these skins, something else had happened too. Like characters with different abilities, or even their own shops.