diff --git a/examples/window.cr b/examples/window.cr
index ef02f5d..a7b2b05 100644
--- a/examples/window.cr
+++ b/examples/window.cr
@@ -1,6 +1,21 @@
 require "./../src/cyberarm_engine"
 
 class Window < CyberarmEngine::Window
+  class State < CyberarmEngine::GameState
+    @options : Int32
+
+    def draw
+      Gosu.draw_rect(0, 0, window.width, window.height, 0xff_353535)
+    end
+
+    def needs_cursor?
+      true
+    end
+  end
+
+  def setup
+    push_state(State.new(3))
+  end
 end
 
-Window.new(width: 700, height: 700).show
\ No newline at end of file
+Window.new.show
\ No newline at end of file
diff --git a/src/cyberarm_engine.cr b/src/cyberarm_engine.cr
index 9149892..dfade47 100644
--- a/src/cyberarm_engine.cr
+++ b/src/cyberarm_engine.cr
@@ -1,7 +1,17 @@
 require "gosu"
 
-module CyberarmEngine
-  VERSION = "0.1.0"
+require "./cyberarm_engine/version"
+require "./cyberarm_engine/window"
+require "./cyberarm_engine/common"
+require "./cyberarm_engine/game_state"
+require "./cyberarm_engine/game_object"
 
-  # TODO: Put your code here
-end
+require "./cyberarm_engine/ui/gui_state"
+require "./cyberarm_engine/ui/dsl"
+require "./cyberarm_engine/ui/event"
+require "./cyberarm_engine/ui/style"
+require "./cyberarm_engine/ui/theme"
+require "./cyberarm_engine/ui/element"
+require "./cyberarm_engine/ui/elements/container"
+require "./cyberarm_engine/ui/elements/stack"
+require "./cyberarm_engine/ui/elements/flow"
\ No newline at end of file
diff --git a/src/cyberarm_engine/common.cr b/src/cyberarm_engine/common.cr
new file mode 100644
index 0000000..a67b9e6
--- /dev/null
+++ b/src/cyberarm_engine/common.cr
@@ -0,0 +1,7 @@
+module CyberarmEngine
+  module Common
+    def window
+      CyberarmEngine::Window.instance.not_nil!
+    end
+  end
+end
\ No newline at end of file
diff --git a/src/cyberarm_engine/game_object.cr b/src/cyberarm_engine/game_object.cr
new file mode 100644
index 0000000..271bc1e
--- /dev/null
+++ b/src/cyberarm_engine/game_object.cr
@@ -0,0 +1,15 @@
+module CyberarmEngine
+  class GameObject
+    def draw
+    end
+
+    def update
+    end
+
+    def button_down(id)
+    end
+
+    def button_up(id)
+    end
+  end
+end
diff --git a/src/cyberarm_engine/game_state.cr b/src/cyberarm_engine/game_state.cr
new file mode 100644
index 0000000..4bd8612
--- /dev/null
+++ b/src/cyberarm_engine/game_state.cr
@@ -0,0 +1,82 @@
+module CyberarmEngine
+  class GameState
+    include Common
+
+    property :options, :global_pause
+    getter :game_objects
+
+      @down_keys : Hash(UInt32, Bool)
+
+    def initialize(@options)
+      @game_objects = [] of GameObject
+      @global_pause = false
+      @down_keys = {} of UInt32 => Bool
+    end
+
+    def setup
+    end
+
+    def post_setup
+    end
+
+    def draw
+      @game_objects.each do |o|
+        o.draw
+      end
+    end
+
+    def update
+      @game_objects.each do |o|
+        o.update
+      end
+    end
+
+    def needs_cursor?
+      true
+    end
+
+    def needs_redraw?
+      true
+    end
+
+    def drop(filename)
+    end
+
+    def gamepad_connected(index)
+    end
+
+    def gamepad_disconnected(index)
+    end
+
+    def gain_focus
+    end
+
+    def lose_focus
+    end
+
+    def button_down(id)
+      @down_keys[id] = true
+
+      @game_objects.each do |o|
+        o.button_down(id)
+      end
+    end
+
+    def button_up(id)
+      @down_keys.delete(id)
+
+      @game_objects.each do |o|
+        o.button_up(id)
+      end
+    end
+
+    def close : Bool
+      CyberarmEngine::Window.instance.not_nil!.close!
+    end
+
+    def destroy
+      @game_objects.each(&:destroy)
+      @game_objects.clear
+    end
+  end
+end
diff --git a/src/cyberarm_engine/image.cr b/src/cyberarm_engine/image.cr
new file mode 100644
index 0000000..0c9095f
--- /dev/null
+++ b/src/cyberarm_engine/image.cr
@@ -0,0 +1,4 @@
+module CyberarmEngine
+  class Image < Gosu::Image
+  end
+end
diff --git a/src/cyberarm_engine/ui/border_canvas.cr b/src/cyberarm_engine/ui/border_canvas.cr
new file mode 100644
index 0000000..e69de29
diff --git a/src/cyberarm_engine/ui/dsl.cr b/src/cyberarm_engine/ui/dsl.cr
new file mode 100644
index 0000000..e69de29
diff --git a/src/cyberarm_engine/ui/element.cr b/src/cyberarm_engine/ui/element.cr
new file mode 100644
index 0000000..e69de29
diff --git a/src/cyberarm_engine/ui/elements/container.cr b/src/cyberarm_engine/ui/elements/container.cr
new file mode 100644
index 0000000..a3e6330
--- /dev/null
+++ b/src/cyberarm_engine/ui/elements/container.cr
@@ -0,0 +1,6 @@
+module CyberarmEngine
+  class Element
+    class Container < Element
+    end
+  end
+end
diff --git a/src/cyberarm_engine/ui/elements/flow.cr b/src/cyberarm_engine/ui/elements/flow.cr
new file mode 100644
index 0000000..11c6d8d
--- /dev/null
+++ b/src/cyberarm_engine/ui/elements/flow.cr
@@ -0,0 +1,15 @@
+module CyberarmEngine
+  class Element
+    class Flow < Container
+      def layout
+        @children.each do |child|
+          if fits_on_line?(child)
+            position_on_current_line(child)
+          else
+            position_on_next_line(child)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/src/cyberarm_engine/ui/elements/stack.cr b/src/cyberarm_engine/ui/elements/stack.cr
new file mode 100644
index 0000000..3558e3f
--- /dev/null
+++ b/src/cyberarm_engine/ui/elements/stack.cr
@@ -0,0 +1,11 @@
+module CyberarmEngine
+  class Element
+    class Stack < Container
+      def layout
+        @children.each do |child|
+          move_to_next_line(child)
+        end
+      end
+    end
+  end
+end
diff --git a/src/cyberarm_engine/ui/event.cr b/src/cyberarm_engine/ui/event.cr
new file mode 100644
index 0000000..e69de29
diff --git a/src/cyberarm_engine/ui/gui_state.cr b/src/cyberarm_engine/ui/gui_state.cr
new file mode 100644
index 0000000..78df7ea
--- /dev/null
+++ b/src/cyberarm_engine/ui/gui_state.cr
@@ -0,0 +1,4 @@
+module CyberarmEngine
+  class GuiState < GameState
+  end
+end
diff --git a/src/cyberarm_engine/ui/style.cr b/src/cyberarm_engine/ui/style.cr
new file mode 100644
index 0000000..e69de29
diff --git a/src/cyberarm_engine/ui/theme.cr b/src/cyberarm_engine/ui/theme.cr
new file mode 100644
index 0000000..e69de29
diff --git a/src/cyberarm_engine/version.cr b/src/cyberarm_engine/version.cr
new file mode 100644
index 0000000..eae7748
--- /dev/null
+++ b/src/cyberarm_engine/version.cr
@@ -0,0 +1,4 @@
+module CyberarmEngine
+  NAME    = "InDev"
+  VERSION = "0.1.0"
+end
\ No newline at end of file
diff --git a/src/cyberarm_engine/window.cr b/src/cyberarm_engine/window.cr
index 62d2738..370f253 100644
--- a/src/cyberarm_engine/window.cr
+++ b/src/cyberarm_engine/window.cr
@@ -1,6 +1,122 @@
 module CyberarmEngine
   class Window < Gosu::Window
-    def initialize(width: 800, height: 600, fullscreen: false, update_interval: 1000.0 / 60, resizable: false, borderless: false)
+    @@instance = nil : CyberarmEngine::Window?
+
+    def self.instance
+      @@instance
+    end
+
+    def self.instance=(klass : CyberarmEngine::Window)
+      @@instance = klass
+    end
+
+    @last_frame_time : UInt64
+    @current_frame_time : UInt64
+
+    def initialize(@width = 800, @height = 600, @fullscreen = false, @update_interval = 1000.0 / 60, @resizable = false, @borderless = false)
+      @has_focus = false
+
+      @last_frame_time = Gosu.milliseconds
+      @current_frame_time = Gosu.milliseconds
+
+      @states = [] of CyberarmEngine::GameState
+      @exit_on_opengl_error = false
+
+      super(@width, @height, @fullscreen, @update_interval, @resizable, @borderless)
+
+      self.caption = "CyberarmEngine.cr v#{CyberarmEngine::VERSION} #{Gosu.language}"
+      CyberarmEngine::Window.instance = self
+
+      setup
+    end
+
+    def setup
+    end
+
+    def draw
+      current_state.not_nil!.draw if current_state
+    end
+
+    def update
+      current_state.not_nil!.update if current_state
+
+      @last_frame_time = Gosu.milliseconds - @current_frame_time
+      @current_frame_time = Gosu.milliseconds
+    end
+
+    def needs_cursor?
+      current_state ? current_state.not_nil!.needs_cursor? : true
+    end
+
+    def needs_redraw?
+      current_state ? current_state.not_nil!.needs_redraw? : true
+    end
+
+    def drop(filename)
+      current_state.not_nil!.drop(filename) if current_state
+    end
+
+    def gamepad_connected(index)
+      current_state.not_nil!.gamepad_connected(index) if current_state
+    end
+
+    def gamepad_disconnected(index)
+      current_state.not_nil!.gamepad_disconnected(index) if current_state
+    end
+
+    def gain_focus
+      current_state.not_nil!.gain_focus if current_state
+    end
+
+    def lose_focus
+      current_state.not_nil!.lose_focus if current_state
+    end
+
+    def button_down(id)
+      current_state.not_nil!.button_down(id) if current_state
+    end
+
+    def button_up(id)
+      current_state.not_nil!.button_up(id) if current_state
+    end
+
+    def close
+      current_state ? current_state.not_nil!.close : super
+    end
+
+    def dt
+      @last_frame_time / 1000.0
+    end
+
+    def aspect_ratio
+      width / height.to_f
+    end
+
+    def exit_on_opengl_error?
+      @exit_on_opengl_error
+    end
+
+    def push_state(instance)
+      @states << instance
+
+      current_state.not_nil!.setup
+      current_state.not_nil!.post_setup
+    end
+
+    def current_state : CyberarmEngine::GameState?
+      @states.last?
+    end
+
+    def pop_state : CyberarmEngine::GameState?
+      @states.pop?
+    end
+
+    def shift_state : CyberarmEngine::GameState?
+      @states.shift?
+    end
+
+    def has_focus?
+      @has_focus
     end
   end
 end