diff --git a/src/ai/fitness.py b/src/ai/fitness.py
new file mode 100644
index 0000000..d1bb757
--- /dev/null
+++ b/src/ai/fitness.py
@@ -0,0 +1,5 @@
+import neat
+
+
+def calculate_fitness(app) -> float | int:
+    return app.game.score + app.game.lines * 100 + app.game.level * 1000