Use score class

src/com/annimon/influencexxii/EnemiesController.java

@@ -47,6 +47,8 @@ public class EnemiesController {
     public void killEnemy(float x, float y) {
         for (int i = 0; i < enemies.size; i++) {
             if (enemies.get(i).isCollide(x, y)) {
+                Score.add();
+                difficultMode = Score.getDifficultMode();
                 enemies.set(i, generateNewEnemy());
                 return;
             }