Adding explorations endpoint

routes/services/invisiblepuzzle/invisiblepuzzle.js

@@ -273,9 +273,11 @@ router.get('/explorations/hpbylevel', function(req, res, next) {
 
             // Stage 3
             {
-                "_id": 1,
-                "explorations": 1,
-                "hp_ratio": {$divide:["$with_hp","$explorations"]}
+                $project: {
+                    "_id": 1,
+                    "explorations": 1,
+                    "hp_ratio": {$divide:["$with_hp","$explorations"]}
+                }
             },
 
             // Stage 4