I am looking to track many in-game events, e.g. the score of each move, how many moves are taken, what types of moves, etc. A lot of stats can simply be tracked with a counter. In some cases I need to aggregate data in order to calculate the value (e.g. most common move). How are you tracking in-game stats for your games? How do you avoid creating a class with tens or hundreds of fields? How do you avoid littering the code with tracking invocations? How do you abstract the aggregate data so as to avoid rewriting it for each scenario?