Add levelling up mechanics through experience gained via killing enemies

src/engine/world/world-logic.ts

@@ -19,11 +19,12 @@ export function isBlocked(w: World, x: number, y: number): boolean {
   if (isWall(w, x, y)) return true;
 
   for (const a of w.actors.values()) {
-    if (a.pos.x === x && a.pos.y === y) return true;
+    if (a.pos.x === x && a.pos.y === y && a.type !== "exp_orb") return true;
   }
   return false;
 }
 
+
 export function isPlayerOnExit(w: World, playerId: EntityId): boolean {
   const p = w.actors.get(playerId);
   if (!p) return false;