diff --git a/testbed/CMakeLists.txt b/testbed/CMakeLists.txt
index 867c897f8..b5d44492b 100644
--- a/testbed/CMakeLists.txt
+++ b/testbed/CMakeLists.txt
@@ -48,6 +48,8 @@ target_sources(
 	PRIVATE
         application/application.cpp
         application/context.cpp
+        system/imgui_system.cpp
+        system/rendering_system.cpp
 		testbed.cpp
         ${imgui_SOURCE_DIR}/backends/imgui_impl_sdl3.cpp
         ${imgui_SOURCE_DIR}/backends/imgui_impl_sdlrenderer3.cpp
diff --git a/testbed/application/application.cpp b/testbed/application/application.cpp
index e1e619ea4..998f7d20b 100644
--- a/testbed/application/application.cpp
+++ b/testbed/application/application.cpp
@@ -4,23 +4,28 @@
 #include <application/context.h>
 #include <backends/imgui_impl_sdl3.h>
 #include <backends/imgui_impl_sdlrenderer3.h>
+#include <entt/entity/registry.hpp>
 #include <imgui.h>
+#include <system/imgui_system.h>
+#include <system/rendering_system.h>
 
 namespace testbed {
 
-void application::update() {
+void application::update(entt::registry &registry) {
     ImGui_ImplSDLRenderer3_NewFrame();
     ImGui_ImplSDL3_NewFrame();
     ImGui::NewFrame();
 
     // update...
+    static_cast<void>(registry);
 }
 
-void application::draw(const context &context) const {
+void application::draw(entt::registry &registry, const context &context) const {
     SDL_SetRenderDrawColor(context, 0u, 0u, 0u, SDL_ALPHA_OPAQUE);
     SDL_RenderClear(context);
 
-    // draw...
+    rendering_system(registry, context);
+    imgui_system(registry);
 
     ImGui::Render();
     ImGuiIO &io = ImGui::GetIO();
@@ -59,12 +64,14 @@ application::~application() {
 }
 
 int application::run() {
+    entt::registry registry{};
     context context{};
+
     quit = false;
 
     while(!quit) {
-        update();
-        draw(context);
+        update(registry);
+        draw(registry, context);
         input();
     }
 
diff --git a/testbed/application/application.h b/testbed/application/application.h
index ae81fbf70..ee5f6ae96 100644
--- a/testbed/application/application.h
+++ b/testbed/application/application.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <SDL3/SDL_events.h>
+#include <entt/entity/fwd.hpp>
 
 struct SDL_Renderer;
 
@@ -10,8 +11,8 @@ struct config;
 struct context;
 
 class application {
-    void update();
-    void draw(const context &) const;
+    void update(entt::registry &);
+    void draw(entt::registry &, const context &) const;
     void input();
 
 public:
diff --git a/testbed/system/imgui_system.cpp b/testbed/system/imgui_system.cpp
new file mode 100644
index 000000000..680cfd530
--- /dev/null
+++ b/testbed/system/imgui_system.cpp
@@ -0,0 +1,16 @@
+#include <entt/entity/registry.hpp>
+#include <imgui.h>
+#include <system/imgui_system.h>
+
+namespace testbed {
+
+void imgui_system(entt::registry &registry) {
+    ImGui::Begin("testbed");
+
+    // ...
+    static_cast<void>(registry);
+
+    ImGui::End();
+}
+
+} // namespace testbed
diff --git a/testbed/system/imgui_system.h b/testbed/system/imgui_system.h
new file mode 100644
index 000000000..15840161c
--- /dev/null
+++ b/testbed/system/imgui_system.h
@@ -0,0 +1,9 @@
+#pragma once
+
+#include <entt/entity/fwd.hpp>
+
+namespace testbed {
+
+void imgui_system(entt::registry &);
+
+} // namespace testbed
diff --git a/testbed/system/rendering_system.cpp b/testbed/system/rendering_system.cpp
new file mode 100644
index 000000000..a41e9b648
--- /dev/null
+++ b/testbed/system/rendering_system.cpp
@@ -0,0 +1,13 @@
+#include <application/context.h>
+#include <entt/entity/registry.hpp>
+#include <system/rendering_system.h>
+
+namespace testbed {
+
+void rendering_system(entt::registry &registry, const context &ctx) {
+    // render...
+    static_cast<void>(registry);
+    static_cast<void>(ctx);
+}
+
+} // namespace testbed
diff --git a/testbed/system/rendering_system.h b/testbed/system/rendering_system.h
new file mode 100644
index 000000000..8bf334705
--- /dev/null
+++ b/testbed/system/rendering_system.h
@@ -0,0 +1,11 @@
+#pragma once
+
+#include <entt/entity/fwd.hpp>
+
+namespace testbed {
+
+struct context;
+
+void rendering_system(entt::registry &, const context &);
+
+} // namespace testbed