diff --git a/assets/schema.json b/assets/schema.json
index c33fab2..eedfb05 100644
--- a/assets/schema.json
+++ b/assets/schema.json
@@ -13,6 +13,9 @@
             "id": {
               "type": "string"
             },
+            "createdAt": {
+              "type": "string"
+            },
             "name": {
               "type": "string"
             },
@@ -28,6 +31,7 @@
           },
           "required": [
             "id",
+            "createdAt",
             "name",
             "players",
             "group",
@@ -45,6 +49,9 @@
             "id": {
               "type": "string"
             },
+            "createdAt": {
+              "type": "string"
+            },
             "name": {
               "type": "string"
             },
@@ -57,19 +64,7 @@
                     "id": {
                       "type": "string"
                     },
-                    "name": {
-                      "type": "string"
-                    }
-                  },
-                  "required": [
-                    "id",
-                    "name"
-                  ]
-                },
-                {
-                  "type": "object",
-                  "properties": {
-                    "id": {
+                    "createdAt": {
                       "type": "string"
                     },
                     "name": {
@@ -78,6 +73,7 @@
                   },
                   "required": [
                     "id",
+                    "createdAt",
                     "name"
                   ]
                 }
@@ -86,6 +82,7 @@
           },
           "required": [
             "id",
+            "createdAt",
             "name",
             "members"
           ]
@@ -101,19 +98,7 @@
             "id": {
               "type": "string"
             },
-            "name": {
-              "type": "string"
-            }
-          },
-          "required": [
-            "id",
-            "name"
-          ]
-        },
-        {
-          "type": "object",
-          "properties": {
-            "id": {
+            "createdAt": {
               "type": "string"
             },
             "name": {
@@ -122,16 +107,12 @@
           },
           "required": [
             "id",
+            "createdAt",
             "name"
           ]
         }
       ]
     }
-  },
-  "required": [
-    "games",
-    "groups",
-    "players"
-  ]
+  }
 }
 
diff --git a/lib/data/dto/game.dart b/lib/data/dto/game.dart
index 30898e5..4188bc4 100644
--- a/lib/data/dto/game.dart
+++ b/lib/data/dto/game.dart
@@ -5,11 +5,11 @@ import 'package:uuid/uuid.dart';
 
 class Game {
   final String id;
+  final DateTime createdAt;
   final String name;
   final List<Player>? players;
   final Group? group;
   final String? winner;
-  final DateTime createdAt;
 
   Game({
     String? id,
@@ -30,6 +30,7 @@ class Game {
   Game.fromJson(Map<String, dynamic> json)
     : id = json['id'],
       name = json['name'],
+      createdAt = DateTime.parse(json['createdAt']),
       players = json['players'] != null
           ? (json['players'] as List)
                 .map((playerJson) => Player.fromJson(playerJson))
@@ -41,6 +42,7 @@ class Game {
   /// Converts the Game instance to a JSON object.
   Map<String, dynamic> toJson() => {
     'id': id,
+    'createdAt': createdAt.toIso8601String(),
     'name': name,
     'players': players?.map((player) => player.toJson()).toList(),
     'group': group?.toJson(),
diff --git a/lib/data/dto/group.dart b/lib/data/dto/group.dart
index 3f00bf5..92dbd09 100644
--- a/lib/data/dto/group.dart
+++ b/lib/data/dto/group.dart
@@ -4,9 +4,9 @@ import 'package:uuid/uuid.dart';
 
 class Group {
   final String id;
+  final DateTime createdAt;
   final String name;
   final List<Player> members;
-  final DateTime createdAt;
 
   Group({
     String? id,
@@ -24,6 +24,7 @@ class Group {
   /// Creates a Group instance from a JSON object.
   Group.fromJson(Map<String, dynamic> json)
     : id = json['id'],
+      createdAt = DateTime.parse(json['createdAt']),
       name = json['name'],
       members = (json['members'] as List)
           .map((memberJson) => Player.fromJson(memberJson))
@@ -32,6 +33,7 @@ class Group {
   /// Converts the Group instance to a JSON object.
   Map<String, dynamic> toJson() => {
     'id': id,
+    'createdAt': createdAt.toIso8601String(),
     'name': name,
     'members': members.map((member) => member.toJson()).toList(),
   };
diff --git a/lib/data/dto/player.dart b/lib/data/dto/player.dart
index f7e05d2..cfb4f4b 100644
--- a/lib/data/dto/player.dart
+++ b/lib/data/dto/player.dart
@@ -3,8 +3,8 @@ import 'package:uuid/uuid.dart';
 
 class Player {
   final String id;
-  final String name;
   final DateTime createdAt;
+  final String name;
 
   Player({String? id, DateTime? createdAt, required this.name})
     : id = id ?? const Uuid().v4(),
@@ -18,8 +18,13 @@ class Player {
   /// Creates a Player instance from a JSON object.
   Player.fromJson(Map<String, dynamic> json)
     : id = json['id'],
+      createdAt = DateTime.parse(json['createdAt']),
       name = json['name'];
 
   /// Converts the Player instance to a JSON object.
-  Map<String, dynamic> toJson() => {'id': id, 'name': name};
+  Map<String, dynamic> toJson() => {
+    'id': id,
+    'createdAt': createdAt.toIso8601String(),
+    'name': name,
+  };
 }