Assets are inside "src" folder:

game-winter
└─src
  ├─sfx
  └─sprites

To run the game, all you need to do is move "sfx" folder to where your executable is. Assuming "debug" and "release" targets, you just have to copy and paste these assets there, and it should run with no problems:

game-winter
├─src
│ ├─sfx (COPY...) 
│ └─sprites (included within executable, so it's not necessary)
|
└─target
  ├─debug
  | ├─sfx (...PASTE)
  | └─game-winter (debug executable)
  └─release
    ├─sfx (...PASTE) 
    └─game-winter (release executable)

The end result should be like this:

(game directory)
├─sfx
| ├─bgm_main.wav
| ├─sfx_fly.wav
| ├─sfx_hit.wav
| ├─sfx_play.wav
| └─sfx_rain.wav
└─game-winter (debug/release executable)

That's why there's a "pack-assets.bat" inside the project folder . I was thinking about using "build.rs", but it ended up being a lot easier to just use a batch file instead. :P

Sorry for the lenghty reply. I hope you can play the game! :D