Snapchat Streaks
A number next to a name that you could not let go to zero.
Consecutive days of messaging tracked with a flame emoji, which turned casual chat into an obligation.
People handed their login to friends to keep streaks alive while on holiday. Genuine distress when a 500-day streak broke was widespread and entirely real.
It is one of the purest pieces of engagement design ever shipped, and everybody saw exactly what it was doing and did it anyway.
Cost back then
Free
Goes for now
Still there, still relentless
