Sustainability Advent Calendar 2025

Daily sustainability challenges throughout December

Archive Mode The live event ended on December 24, 2025. All 24 challenges stay open to play with no login and no database writes.

🗂️ Playable Archive

The Sustainability Advent Calendar campaign ran from December 1 to December 24, 2025. The full set of 24 challenges is now permanently open for practice and learning.

  • No login required
  • No database writes
  • Progress is saved locally in your current browser only