It´s so important the level progression of the people and analyze everything ...
I propose a new feature
Level progression average every day for every user and the levels completed on the last days
Day 1 : 5 Levels completed / average - Level 1 to 5 ( 20 mins played )
Day 2 : 7 Levels completed / average - Level 5 to 12 ( 24 mins played )
Day 3 : 3 levels completed / average - Level 13 to 16 ( 15 mins played )
And cross this data with the retention for the next days ( included testing a/b with different levels & game versions )
Day 1: User retention
Day 2: User retention - ( 90 % of last , play again on the next day )
Day 3: User retention ( 80% of last step play again on the next day )
Day 4: User retention ( 40% of last step play again on the next day ) ¿ excesive difficulty or hard levels is not funny?
Identify the excesive frustration on hard levels
Game levels can be hard, but can be fun, identify levels that aren't fun is essential viewing in the statistics if they return the next day