I had thought about the corner thing but literally have not time to correct it, I think most games spawn a enemy in the corner that kills you so you can not be in the corner a lot, but not sure. The same about the enemies spawning to close but I didn´t liked to spawn all of them outside of the player view, I have to tune the distance and the enemy speeds.
About the music I was not sure what format was the better. I imagine .ogg weight less than .wav but did not checked.
Thanks for the feedback! For sure I will try to tune the gameplay and have a little but finished game.