diff --git a/game-schema-d4.json b/game-schema-d4.json
index ed407bd4..1c6f8095 100644
--- a/game-schema-d4.json
+++ b/game-schema-d4.json
@@ -1,25 +1,39 @@
 {
     "$schema": "http://json-schema.org/draft-07/schema#",
-    "$id": "https://raw.githubusercontent.com/gbdev/database/master/game-schema-d3.json",
-    "title": "Game object",
-    "description": "A game in the Homebrew Hub database",
+    "$id": "https://raw.githubusercontent.com/gbdev/database/master/game-schema-d4.json",
+    "title": "Game manifest",
+    "description": "Describes a software entry in the Homebrew Hub database, mentioning metadata and related assets (such as ROM files).",
     "type": "object",
+    "additionalProperties": false,
     "properties":
     {
         "slug":
         {
-            "description": "A unique string identifier for a game",
-            "type": "string"
+            "description": "A unique string identifier for a game. Letters, numbers, the 'en' dash and the dot are the only allowed characters.",
+            "type": "string",
+            "pattern": "^[A-Za-z0-9]+(?:-[A-Za-z0-9.]+)*$"
         },
         "developer":
         {
-            "type": "string",
-            "description": "A name, username or nickname representing the developer(s)"
+            "description": "A name, username or nickname representing the developer(s)",
+            "anyof":
+            [
+                {
+                    "type": "array",
+                    "items":
+                    {
+                        "type": "string"
+                    }
+                },
+                {
+                    "type": "string"
+                }
+            ]
         },
         "description":
         {
             "type": "string",
-            "description": "A text description about the entry (e.g. Instructions, lore, ..)"
+            "description": "A brief, plain text description about the entry"
         },
         "title":
         {
@@ -30,13 +44,25 @@
         {
             "type": "string",
             "description": "Target console",
-            "enum": ["GB", "GBC", "GBA"]
+            "enum":
+            [
+                "GB",
+                "GBC",
+                "GBA"
+            ]
         },
         "typetag":
         {
             "type": "string",
             "description": "Type of the software",
-            "enum": ["game", "homebrew", "demo", "hackrom", "music"]
+            "enum":
+            [
+                "game",
+                "tool",
+                "demo",
+                "hackrom",
+                "music"
+            ]
         },
         "gameLicense":
         {
@@ -59,6 +85,21 @@
             "format": "date",
             "description": "The date the entry was first released"
         },
+        "features":
+        {
+            "type": "array",
+            "description": "A list of the addional supported features",
+            "items":
+            {
+                "type": "string",
+                "enum":
+                [
+                    "gbprinter",
+                    "gbcamera",
+                    "sgb"
+                ]
+            }
+        },
         "tags":
         {
             "type": "array",
@@ -66,7 +107,18 @@
             "items":
             {
                 "type": "string",
-                "enum": ["RPG", "Open Source", "Adventure", "Action", "Puzzle", "Platform", "gbajam21", "gbcompo21", "gbcompo21-shortlist", "gbprinter"]
+                "enum":
+                [
+                    "RPG",
+                    "Open Source",
+                    "Adventure",
+                    "Action",
+                    "Puzzle",
+                    "Platform",
+                    "gbajam21",
+                    "gbcompo21",
+                    "gbcompo21-shortlist"
+                ]
             }
         },
         "alias":
@@ -128,9 +180,11 @@
                 "$ref": "#/definitions/file"
             }
         }
-
     },
-    "required": ["slug"],
+    "required":
+    [
+        "slug"
+    ],
     "definitions":
     {
         "file":
@@ -146,9 +200,20 @@
                 {
                     "type": "string"
                 },
-                "type": {
+                "type":
+                {
+                    "type": "string",
+                    "enum":
+                    [
+                        "rom",
+                        "manual",
+                        "release"
+                    ]
+                },
+                "version":
+                {
                     "type": "string",
-                    "enum": ["rom", "manual", "release"]
+                    "description": "Specify game version this file refers to. More files can be grouped under the same version"
                 },
                 "playable":
                 {
@@ -178,14 +243,46 @@
                 {
                     "type": "boolean",
                     "description": "Describes if the file is the default ROM to play"
+                },
+                "baserom":
+                {
+                    "type": "object",
+                    "description": "Base ROM required for the patch to be applied",
+                    "properties":
+                    {
+                        "filename":
+                        {
+                            "type": "string"
+                        },
+                        "md5":
+                        {
+                            "type": "string"
+                        },
+                        "sha1":
+                        {
+                            "type": "string"
+                        },
+                        "sha256":
+                        {
+                            "type": "string"
+                        },
+                        "crc32":
+                        {
+                            "type": "string"
+                        }
+                    }
                 }
             },
-            "required": ["filename"]
+            "required":
+            [
+                "filename"
+            ]
         },
         "license":
         {
             "type": "string",
-            "enum": [
+            "enum":
+            [
                 "0BSD",
                 "AAL",
                 "Abstyles",
@@ -540,7 +637,6 @@
                 "ZPL-2.0",
                 "ZPL-2.1"
             ]
-
         }
     }
 }