For my simple MMO, the MySQL database stores things like user experience, user level, user coins, health points, etc.
We wanna have an analytics system that can show me trends through daily averages, medians, totals of different stats and actions of the game's user base.
Some answers that need to be answered by this analytics system:
Average health points over time
How many users are what level over time
How many quests were started by users over time vs how many were completed
Cohort analysis on certain groups of users
I was looking into BI systems and thought maybe building an OLAP database with a star schema might be appropriate. But I'm not sure what are good dimensions to use for this and how to deal with changes to the transactional database over time. And it seems like a lot of work to build out a ETL and reporting system as well.
Anything else that's simpler and yet still robust? Are key-value datastores a good option? What are some commonly used systems for doing this type of analytics?