Make a Big Black Sniper

After the protagonist steps into the starry sky door of an antique store, he spends his entire life worrying about the system. How to make a train that doesn't use rails and still travels at full speed. How to make a big black sniper that can shoot without bullets. Why did the prepared hemostatic powder turn into black medicine? I scratch my head about this every day. There is also a group of demon friends that trouble him, There is a green snake girl who needs spiritual stones as snacks. There is a shot weasel boy who needs a big sword, one person tall. Is there a little demon that has not transformed yet and wants to escape? There is a timid Ah Piao who wants to be beaten to death. There are Shamate Fox Uncle and others who like non-mainstream characters. The protagonist completes the system and improves his strength. On the one hand, he acts chivalrously, eliminates violence and saves the world. To put it bluntly, in fact, life is pretty good.