I read rules and it says that i can use anything that has no affect on game overflow so i was wondering can i use particle sistem and its effects like explosion or something like that.
Anything from the package manager(in the case of unity) or anything that is built into the engine itself is allowed, according to the rules. You'd just have to create the textures for the particles.
No, you can't use pre-created textures, such as those from the standard assets pack. You could make your own textures in image creation software like Photoshop, krita, or gimp.
