Thanks for the ideas and comments. About bugs:
1- The sticker bug is now fixed in the latest version 9.4.8
2. During the kill the space background is normal, in the future I hope I can redo it so that the animation is on the location where everything happens.
In general some of the flaws and limitations of the game are due to the fact that it is primarily for mobile devices, for PC the only advantage so far is the higher resolution textures.