Ah, I see. :)
So, extras for Machinarium, here on GOG, include:
- wallpapers: 8 wallpapers in 4 screen resolutions (1280x1024, 1600x1200, 1920x1080, 1920x1200) each;
- soundtrack: 14 .MP3s with music from the game;
- avatars: 8 avatars (150x150 px) cut-out from the game graphics;
- behind the scenes: see my post above;
- artworks: 22 pictures with artworks from the game;
- design sketches: 114 pictures with design sketches for the game.