Nice game in my opinion the best, but there are some notes I would like to make:
first: very nice that you have made several options to play, but the most important is the online one because many people don't want to download the game.
Second: the boss has the sprite a bit bugged
Third: you should keep the game the same throughout the game. I mean you don't have to change the way of life.
Fourth: I don't understand why you made sure that the player has six lives in the boos fight but the boss does only two of damage. Give it three lives and have it do 3 damage.
The game looks good but it's pretty much just luck as there is no way to understand where the asteroids will come from and often you will find them in front of you without being able to dodge them. The commands are convenient from the phone but could be optimized from a PC.
I must say that it's not bad, moreover the movement of the character makes everything playable even from the phone but I would still like to give some advice.
First: the pixel have different size and you should avoid this, if you use unity when you import the sprite in the inspector, under pixel per unity set the dimension of the sprite.
Second: I don't understand what the explosive box is, I suggest you specify it when you interpret it in a more abstract way.
Third: you should explain what are the objects that are obtained in the game because the effect is not understood.
Fourth: you should add a difficulty boost to the game as it is quite simple. If there is already I would mark him more.
