diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index fec6fc1..4dd37f2 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -18,6 +18,11 @@ general-packages:
   inherit:
     default: [before_script, image]
   script:
+    # Gazebo security freeimage-unstable-2021-11-01’ is marked as insecure
+    #   /nix/store/28gcncrir6wd8n6n762y92lbm632cxcy-gazebo-sim
+    # └───/nix/store/bw3nx4nrvwbnj9b6hdg4p0iyxnakqca8-gz-common5-5.4.2
+    #     └───/nix/store/hwr0f25hiqv1pjnqyg0sp1gv9grb198b-freeimage-unstable-2021-11-01
+    - export NIXPKGS_ALLOW_INSECURE=1
     - cachix watch-exec robossembler -- nix develop .#all --impure -c echo "General Packages is BUILT"
 
 ros-packages:
diff --git a/flake.lock b/flake.lock
index 4c7879f..ed81be7 100644
--- a/flake.lock
+++ b/flake.lock
@@ -1,6 +1,21 @@
 {
   "nodes": {
     "flake-utils": {
+      "locked": {
+        "lastModified": 1659877975,
+        "narHash": "sha256-zllb8aq3YO3h8B/U0/J1WBgAL8EX5yWf5pMj3G0NAmc=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "c0e246b9b83f637f4681389ecabcb2681b4f3af0",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "flake-utils_2": {
       "inputs": {
         "systems": "systems"
       },
@@ -18,7 +33,67 @@
         "type": "github"
       }
     },
+    "gazebo": {
+      "inputs": {
+        "flake-utils": [
+          "ros-flake",
+          "flake-utils"
+        ],
+        "nixgl": "nixgl",
+        "nixpkgs": [
+          "ros-flake",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1711612492,
+        "narHash": "sha256-QEz9HZCth8kxz8nrqZ9/hhomAfSW6E0ngmoIb00NXQ8=",
+        "owner": "movefasta",
+        "repo": "gazebo-sim-overlay",
+        "rev": "4f1c3c115b55795ec7d7af43d0b16f7ef18dcc44",
+        "type": "github"
+      },
+      "original": {
+        "owner": "movefasta",
+        "repo": "gazebo-sim-overlay",
+        "type": "github"
+      }
+    },
+    "nixgl": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      },
+      "locked": {
+        "lastModified": 1685908677,
+        "narHash": "sha256-E4zUPEUFyVWjVm45zICaHRpfGepfkE9Z2OECV9HXfA4=",
+        "owner": "guibou",
+        "repo": "nixGL",
+        "rev": "489d6b095ab9d289fe11af0219a9ff00fe87c7c5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "guibou",
+        "repo": "nixGL",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
+      "locked": {
+        "lastModified": 1660551188,
+        "narHash": "sha256-a1LARMMYQ8DPx1BgoI/UN4bXe12hhZkCNqdxNi6uS0g=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "441dc5d512153039f19ef198e662e4f3dbb9fd65",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
       "locked": {
         "lastModified": 1712307699,
         "narHash": "sha256-/PzHcPvBvJeZTY9JCEtbNljYLecwggveHQ2oHPlTycA=",
@@ -34,7 +109,7 @@
         "type": "github"
       }
     },
-    "nixpkgs_2": {
+    "nixpkgs_3": {
       "locked": {
         "lastModified": 1707268954,
         "narHash": "sha256-2en1kvde3cJVc3ZnTy8QeD2oKcseLFjYPLKhIGDanQ0=",
@@ -56,14 +131,15 @@
           "ros-flake",
           "flake-utils"
         ],
-        "nixpkgs": "nixpkgs",
+        "gazebo": "gazebo",
+        "nixpkgs": "nixpkgs_2",
         "ros-flake": "ros-flake"
       }
     },
     "ros-flake": {
       "inputs": {
-        "flake-utils": "flake-utils",
-        "nixpkgs": "nixpkgs_2"
+        "flake-utils": "flake-utils_2",
+        "nixpkgs": "nixpkgs_3"
       },
       "locked": {
         "lastModified": 1711215320,
diff --git a/flake.nix b/flake.nix
index 5e8e25a..dd15bcd 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,15 +4,26 @@
     nixpkgs.url = "github:NixOS/nixpkgs?ref=master";
     flake-utils.follows = "ros-flake/flake-utils";
     ros-flake.url = "github:lopsided98/nix-ros-overlay?ref=develop";
+    gazebo = {
+      url = "github:movefasta/gazebo-sim-overlay";
+      inputs.flake-utils.follows = "ros-flake/flake-utils";
+      inputs.nixpkgs.follows = "ros-flake/nixpkgs";
+
+      # Transitive inputs "not in registry" https://github.com/NixOS/nix/issues/5790
+      # inputs.nixgl.inputs.nixpkgs.follows = "ros-flake/nixpkgs";
+      # inputs.nixgl.inputs.flake-utils.follows = "ros-flake/flake-utils";
+    };
   };
 
-  outputs = { self, nixpkgs, ros-flake, flake-utils }:
+  outputs = { self, nixpkgs, ros-flake, gazebo, flake-utils }:
     flake-utils.lib.eachDefaultSystem
       (system:
         let
-          pkgs = nixpkgs.legacyPackages.${system}.extend overlay;
+          # pkgs = nixpkgs.legacyPackages.${system}.extend overlay;
           ros = ros-flake.legacyPackages.${system};
 
+          pkgs = import nixpkgs { inherit system; overlays = [ overlay gazebo.overlays.default ]; };
+
           overlay = final: prev: {
             # -- PLACEHOLDER for overlay
             # freecad = prev.freecad.overrideAttrs
@@ -139,6 +150,8 @@
 
           devShells.ci = pkgs.mkShell { buildInputs = [ pkgs.jq ]; };
 
+          devShells.gazebo = gazebo.devShells.${system}.default;
+
           devShells.ros = 
             pkgs.mkShell {
               buildInputs = (with humble-overrided; [
@@ -173,7 +186,7 @@
                 image-transport
                 cv-bridge
                 example-interfaces
-              ]) ++ (with pkgs; [ nlohmann_json glog lua5_3_compat ]);
+              ]) ++ (with pkgs; [ nlohmann_json glog lua5_3_compat gazebo_sim ]);
               RMW_IMPLEMENTATION = "rmw_fastrtps_dynamic_cpp";
             };