Here is the full list of all 20 Recursion Deluxe achievements.
Completed Sky Temple!
Collected every star in Sky Temple!
Completed Honey Swamp without dying!
Completed Honey Swamp!
Collected every star in Honey Swamp!
Completed Bumbling Plains without dying!
Completed Bumbling Plains!
Collected every star in Bumbling Plains!
Completed Sky Temple without dying!
Completed Ancient Hive!
Collected every star in Ancient Hive!
Completed Ancient Hive without dying!
Built and play-tested a custom level!
Found a hidden statue and conquered its challenge!