Interface parameters lowercase.

src/game/SaveGame.test.ts

@@ -3,8 +3,8 @@ import { saveGameKey, saveGame, loadGame } from './SaveGame';
 
 describe("SaveGame", () => {
     const state = {
-        Level: 42,
-        Score: 89,
+        level: 42,
+        score: 89,
     };
 
     beforeEach(() => {

src/game/SaveGame.ts

@@ -1,8 +1,8 @@
 export const saveGameKey = "save_game";
 
 export interface SaveGame {
-    Level: number
-    Score: number
+    level: number
+    score: number
 }
 
 export function saveGame(saveGame: SaveGame) {