There is a small pack of art, music and HR backgrounds. It doesn't change anything in the game, it's just an opportunity to say "Thanks" to the authors and help them with releasing their following projects, also it's the way to bind the game to your Steam games list.

After installing DLC all the materials can be found in the folder "Evening Surprise" named "Extra".

List of materials:
Music in "wav" format:

• ES (Evening Surprise main theme)
  
• Romantic Theme
  
• Intense Theme
  
• Main Menu Theme
  
• Mystic Theme
  
• Underwater Theme
  
• Thoughts Theme
  
• Final Theme

Arts in "psd" format:

• Heroes arts
  
• Final art
  
• Ocean art
  
• Street art
  
• Spider art

Arts in "png" format:

• Bedroom night\day arts
  
• Hall art
  
• Hall 2 art
  
• Lounge night\day arts
  
• Kitchen day\candles arts