Hello, WayForwardKalius. You are probably unexperienced, so I will try to explain it to you. Asking the developer for the source code of the game is at the very least not polite. You should also know that using textures from other games has serious consequences. The developer can easily remove your game from public sites, or even worse - sue you. I just wanted to warn you, because once in my childhood, when I created my first game, I did not know all this, and I got into serious trouble.
If you want to start making games, achieve this with your own efforts, and not the efforts of other developers. Try to create unique and fun games! Good luck to you!