Fix mass not being settable

src/game/creature.ts

@@ -47,6 +47,9 @@ export class Creature extends Vore implements Combatant {
         const adjusted = self.effects.reduce((scale: number, effect: Effective) => effect.scale(scale), base)
         return adjusted
       },
+      set [VoreStat.Mass] (mass: number) {
+        baseVoreStats.Mass = mass
+      },
       get [VoreStat.PreyCount] () {
         return baseVoreStats["Prey Count"]
       }