BasicStats

pub struct BasicStatTemplate {
    pub index: u16,
    pub name: String,
    pub stat_type: BasicStatType,
    pub inherited: InheritanceState,
}

pub struct BasicStat {
    pub index: u16,
    pub state: BasicStatState,
}

All PlayerClasses define an optional vec of BasicStatTemplates that will map 1:1 to BasicStats in Players when instantiated. The Template defines what kind of stat it is, as well as its name, and the actual BasicStat contains the current state for that stat. An example BasicStat is "health," which might have a min/max of 0/100, and could be 50 on one Player and 60 on another.

You'll notice the use of index on both structs. This is to assist in matching across both Player and PlayerClass in a more stable way than name.

The meat of a BasicStatTemplate is the BasicStatType, defined below:

pub enum BasicStatType {
    Enum {
        starting: u8,
        values: Vec<Threshold>,
    },
    Integer {
        min: Option<i64>,
        max: Option<i64>,
        starting: i64,
        staking_amount_scaler: Option<u64>,
        staking_duration_scaler: Option<u64>,
    },
    Bool {
        starting: bool,
        staking_flip: Option<u64>,
    },
    String {
        starting: String,
    },
}

It is an enum that defines all the information a Player would need to know to govern a stat of a given type as that stat moves in value over time. The actual state, called a BasicStatState, is defined thusly:

pub enum BasicStatState {
    Enum {
        current: u8,
    },
    Integer {
        base: i64,
        with_temporary_changes: i64,
        temporary_numerator: i64,
        temporary_denominator: i64,
        finalized: i64,
    },
    Bool {
        current: bool,
    },
    String {
        current: String,
    },
    Null,
} 

With most of the data types the state is only pointing at the current value. The tricky part comes for Integers, which need to keep track of a bunch of intermediate values to track how items, both equipped and used, change the stat over time. When the contract "does math," it uses both structs in memory to figure out where to position the current value next, however your Player PDA is much smaller than the PlayerClass it inherits from because it doesn't need to keep track of mins, maxes, or all possible values.

If you need a more complex type of data field than those provided here, the stats URI provided to every Player by its PlayerClass may be the right fit for you. You can store any type of data you want there, but it's up to you to handle changes to it and logic with it.