A badge is an achievement that is not lost between game sessions.
Some badges have several levels, higher level badges replacing the corresponding lower level ones.
In addition to standard badges that are obtained by doing actions in a given game session, there are super badges that are obtained by doing actions in multiple game sessions (because doing all the required actions in one session is technically impossible).
The badge “Amulet of Yendor obtained” is not displayed anymore when the super badge “Amulet of Yendor obtained by Warrior, Mage, Rogue & Huntress” is obtained.
Fighting
7 hit combo
Level completed without killing any monsters
Monster killed by a Grim weapon
6 piranhas killed
Badges with different levels
Each badge takes only the current game session into account, the counters start at 0 for each new game.