логика выделена в отдельный набор классов

src/game/upgrades.ts

@@ -88,7 +88,7 @@ export const UPGRADE_LIST: UpgradeDef[] = [
     // Game-hours per real second during morning/day/evening (16 game-hours by default spread
     // over the default 10s day-phase of the 20s day-night cycle) — night has its own fixed speed.
     effectAtLevel: (level) => 16 * Math.pow(1.15, level - 1),
-    formatEffect: (v, level) => `${v.toFixed(0)} с`,
+    formatEffect: (v) => `${v.toFixed(0)} с`,
   },
   {
     id: 'maxHealth',