What surprised me wasn’t the growth, but player behavior.
I added a daily leaderboard mostly as a nice extra. No rewards, no social sharing, no incentives.
Players started replaying puzzles obsessively just to improve rank. Some would finish a level and immediately restart to shave off seconds.
It ended up driving more repeat sessions than progression itself.
Lesson learned: In logic games, light competition can outperform progression, even without rewards.