Activity Level

Activity Level was a hidden STAT that, hence the name, recorded someone's level of activity in their life. Unlike other STATs, it could only be accessed via the Void instead of the SOUL. Therefore, only someone outside time and space could read anybody's Activity Levels, including their own.

The only Activity Level seen was Frisk's, which was recorded in stages: when they reached a large point in each timeline they created, they gained an Activity Level. They were currently at Activity Level C.