This DLC provides no in-game content or additions. Everything in the game is available to everyone for free, forever.

The DLC is intended as a way to show your support for the developers.
It'll allow us to keep making games, and keep releasing them for free and unpaywalled.

That being said, this DLC does include out of game content:

• Skill Tree Wallpaper 4k
  
• Dalmati Wallpaper 1k
  
• Them Showcase Base Wallpaper 1k, both Caged and Uncaged
  
• Graphical Number PNGs 0-10, in: white/clearbacking; orange/clearbacking; orange/blackbacking
  
• Them Showcase Advanced Wallpaper 1k, both Caged and Uncaged

Also, feel free to indulge in one unit of maniacal cackling for having brought about a miniscule improvement to the games industry. Perfectly timed lightning optional.