I focused on making the gameplay matter, not the images. That's why there are so many variables accessible in the sandbox menu, you can make your own game to your own taste.
You can also use your own images if you don't like the ones in the game:
1- Images must be of 1650x1020px size.
2- Put them in the custom_images folder in the game folder.
3- Check to use custom images in the main menu, or to use only custom images.