diff --git a/lib/cyberarm_engine.rb b/lib/cyberarm_engine.rb
index e24ff41..88fd416 100644
--- a/lib/cyberarm_engine.rb
+++ b/lib/cyberarm_engine.rb
@@ -66,6 +66,6 @@ require_relative "cyberarm_engine/model/material"
 require_relative "cyberarm_engine/model/model_object"
 require_relative "cyberarm_engine/model/parser"
 require_relative "cyberarm_engine/model/parsers/wavefront_parser"
-require_relative "cyberarm_engine/model/parsers/collada_parser" if defined?(Nokogiri)
+require_relative "cyberarm_engine/model/parsers/collada_parser" if RUBY_ENGINE != "mruby" && defined?(Nokogiri)
 
 require_relative "cyberarm_engine/builtin/intro_state"
diff --git a/lib/cyberarm_engine/builtin/intro_state.rb b/lib/cyberarm_engine/builtin/intro_state.rb
index 6c323c8..d37bc96 100644
--- a/lib/cyberarm_engine/builtin/intro_state.rb
+++ b/lib/cyberarm_engine/builtin/intro_state.rb
@@ -18,7 +18,7 @@ module CyberarmEngine
 
       @gosu_logo = generate_proxy("Gosu",     "Game Library",         0xff_111111)
       @ruby_logo = generate_proxy("Ruby",     "Programming Language", 0xff_880000)
-      @opengl_logo = generate_proxy("OpenGL", "Graphics API",         0xff_5586a4) if defined?(OpenGL)
+      @opengl_logo = generate_proxy("OpenGL", "Graphics API",         0xff_5586a4) if RUBY_ENGINE != "mruby" && defined?(OpenGL)
 
       base_time = Gosu.milliseconds
 
diff --git a/lib/cyberarm_engine/common.rb b/lib/cyberarm_engine/common.rb
index 3532a61..4fc8894 100644
--- a/lib/cyberarm_engine/common.rb
+++ b/lib/cyberarm_engine/common.rb
@@ -52,7 +52,7 @@ module CyberarmEngine
     end
 
     def lighten(color, amount = 25)
-      if defined?(color.alpha)
+      if color.respond_to?(:alpha)
         Gosu::Color.rgba(color.red + amount, color.green + amount, color.blue + amount, color.alpha)
       else
         Gosu::Color.rgb(color.red + amount, color.green + amount, color.blue + amount)
@@ -60,7 +60,7 @@ module CyberarmEngine
     end
 
     def darken(color, amount = 25)
-      if defined?(color.alpha)
+      if color.respond_to?(:alpha)
         Gosu::Color.rgba(color.red - amount, color.green - amount, color.blue - amount, color.alpha)
       else
         Gosu::Color.rgb(color.red - amount, color.green - amount, color.blue - amount)
diff --git a/lib/cyberarm_engine/console.rb b/lib/cyberarm_engine/console.rb
index bb23f87..29e59de 100644
--- a/lib/cyberarm_engine/console.rb
+++ b/lib/cyberarm_engine/console.rb
@@ -103,7 +103,7 @@ module CyberarmEngine
 
     def button_down(id)
       case id
-      when Gosu::KbEnter, Gosu::KbReturn
+      when Gosu::KB_ENTER, Gosu::KB_RETURN
         return unless @text_input.text.length.positive?
 
         @history.text += "\n<c=999999>> #{@text_input.text}</c>"
@@ -113,12 +113,12 @@ module CyberarmEngine
         handle_command
         @text_input.text = ""
 
-      when Gosu::KbUp
+      when Gosu::KB_UP
         @command_history_index -= 1
         @command_history_index = 0 if @command_history_index.negative?
         @text_input.text = @command_history[@command_history_index]
 
-      when Gosu::KbDown
+      when Gosu::KB_DOWN
         @command_history_index += 1
         if @command_history_index > @command_history.size - 1
           @text_input.text = "" unless @command_history_index > @command_history.size
@@ -127,7 +127,7 @@ module CyberarmEngine
           @text_input.text = @command_history[@command_history_index]
         end
 
-      when Gosu::KbTab
+      when Gosu::KB_TAB
         split = @text_input.text.split(" ")
 
         if !@text_input.text.end_with?(" ") && split.size == 1
@@ -142,7 +142,7 @@ module CyberarmEngine
           cmd.autocomplete(self)
         end
 
-      when Gosu::KbBacktick
+      when Gosu::KB_BACKTICK
         # Remove backtick character from input
         @text_input.text = if @text_input.text.size > 1
                              @text_input.text[0..@text_input.text.size - 2]
@@ -151,7 +151,7 @@ module CyberarmEngine
                            end
 
       # Copy
-      when Gosu::KbC
+      when Gosu::KB_C
         if control_down? && shift_down?
           @memory = @text_input.text[caret_start..caret_end - 1] if caret_start != caret_end
           p @memory
@@ -160,7 +160,7 @@ module CyberarmEngine
         end
 
       # Paste
-      when Gosu::KbV
+      when Gosu::KB_V
         if control_down? && shift_down?
           string = @text_input.text.chars.insert(caret_pos, @memory).join
           _caret_pos = caret_pos
@@ -170,7 +170,7 @@ module CyberarmEngine
         end
 
       # Cut
-      when Gosu::KbX
+      when Gosu::KB_X
         if control_down? && shift_down?
           @memory = @text_input.text[caret_start..caret_end - 1] if caret_start != caret_end
           string  = @text_input.text.chars
@@ -182,7 +182,7 @@ module CyberarmEngine
         end
 
       # Delete word to left of caret
-      when Gosu::KbW
+      when Gosu::KB_W
         if control_down?
           split = @text_input.text.split(" ")
           split.delete(split.last)
@@ -190,7 +190,7 @@ module CyberarmEngine
         end
 
       # Clear history
-      when Gosu::KbL
+      when Gosu::KB_L
         @history.text = "" if control_down?
       end
     end
diff --git a/lib/cyberarm_engine/game_object.rb b/lib/cyberarm_engine/game_object.rb
index e4cd6ec..0ecd846 100644
--- a/lib/cyberarm_engine/game_object.rb
+++ b/lib/cyberarm_engine/game_object.rb
@@ -42,7 +42,7 @@ module CyberarmEngine
         @radius = if options[:radius]
                     options[:radius]
                   else
-                    defined?(@image.width) ? ((@image.width + @image.height) / 4) * scale : 1
+                    @image.respond_to?(:width) ? ((@image.width + @image.height) / 4) * scale : 1
                   end
       end
     end
diff --git a/lib/cyberarm_engine/text.rb b/lib/cyberarm_engine/text.rb
index e632088..f697322 100644
--- a/lib/cyberarm_engine/text.rb
+++ b/lib/cyberarm_engine/text.rb
@@ -149,6 +149,8 @@ module CyberarmEngine
     end
 
     def markup_width(text = @text)
+      text = text.to_s
+
       spacing = 0
       spacing += @border_size if @border
       spacing += @shadow_size if @shadow
diff --git a/lib/cyberarm_engine/ui/element.rb b/lib/cyberarm_engine/ui/element.rb
index 64d439b..758dca9 100644
--- a/lib/cyberarm_engine/ui/element.rb
+++ b/lib/cyberarm_engine/ui/element.rb
@@ -196,7 +196,7 @@ module CyberarmEngine
     end
 
     def enter(_sender)
-      @focus = false unless window.button_down?(Gosu::MsLeft)
+      @focus = false unless Gosu.button_down?(Gosu::MS_LEFT)
 
       if !@enabled
         update_styles(:disabled)
@@ -316,7 +316,8 @@ module CyberarmEngine
     end
 
     def debug_draw
-      return if defined?(GUI_DEBUG_ONLY_ELEMENT) && self.class == GUI_DEBUG_ONLY_ELEMENT
+      # FIXME
+      return# if const_defined?(GUI_DEBUG_ONLY_ELEMENT) && self.class == GUI_DEBUG_ONLY_ELEMENT
 
       Gosu.draw_line(
         x, y, @debug_color,
diff --git a/lib/cyberarm_engine/ui/elements/text_block.rb b/lib/cyberarm_engine/ui/elements/text_block.rb
index bb185af..c00cc1b 100644
--- a/lib/cyberarm_engine/ui/elements/text_block.rb
+++ b/lib/cyberarm_engine/ui/elements/text_block.rb
@@ -156,7 +156,7 @@ module CyberarmEngine
       end
 
       def line_width(text)
-        (@text.textobject.markup_width(text) + noncontent_width)
+        (@text.textobject.markup_width(text.to_s) + noncontent_width)
       end
 
       def value
diff --git a/lib/cyberarm_engine/ui/gui_state.rb b/lib/cyberarm_engine/ui/gui_state.rb
index 2f259c9..d4455f8 100644
--- a/lib/cyberarm_engine/ui/gui_state.rb
+++ b/lib/cyberarm_engine/ui/gui_state.rb
@@ -63,7 +63,8 @@ module CyberarmEngine
         @tip.draw
       end
 
-      if defined?(GUI_DEBUG)
+      # FIXME
+      if false# defined?(GUI_DEBUG)
         Gosu.flush
 
         @root_container.debug_draw
@@ -121,9 +122,9 @@ module CyberarmEngine
       @mouse_over.publish(:leave) if @mouse_over && new_mouse_over != @mouse_over
       @mouse_over = new_mouse_over
 
-      redirect_holding_mouse_button(:left) if @mouse_over && Gosu.button_down?(Gosu::MsLeft)
-      redirect_holding_mouse_button(:middle) if @mouse_over && Gosu.button_down?(Gosu::MsMiddle)
-      redirect_holding_mouse_button(:right) if @mouse_over && Gosu.button_down?(Gosu::MsRight)
+      redirect_holding_mouse_button(:left) if @mouse_over && Gosu.button_down?(Gosu::MS_LEFT)
+      redirect_holding_mouse_button(:middle) if @mouse_over && Gosu.button_down?(Gosu::MS_MIDDLE)
+      redirect_holding_mouse_button(:right) if @mouse_over && Gosu.button_down?(Gosu::MS_RIGHT)
 
       if Vector.new(window.mouse_x, window.mouse_y) == @last_mouse_pos
         if @mouse_over && (Gosu.milliseconds - @mouse_moved_at) > tool_tip_delay
@@ -151,13 +152,13 @@ module CyberarmEngine
       super
 
       case id
-      when Gosu::MsLeft
+      when Gosu::MS_LEFT
         redirect_mouse_button(:left)
-      when Gosu::MsMiddle
+      when Gosu::MS_MIDDLE
         redirect_mouse_button(:middle)
-      when Gosu::MsRight
+      when Gosu::MS_RIGHT
         redirect_mouse_button(:right)
-      when Gosu::KbF5
+      when Gosu::KB_F5
         request_recalculate
       end
 
@@ -168,15 +169,15 @@ module CyberarmEngine
       super
 
       case id
-      when Gosu::MsLeft
+      when Gosu::MS_LEFT
         redirect_released_mouse_button(:left)
-      when Gosu::MsMiddle
+      when Gosu::MS_MIDDLE
         redirect_released_mouse_button(:middle)
-      when Gosu::MsRight
+      when Gosu::MS_RIGHT
         redirect_released_mouse_button(:right)
-      when Gosu::MsWheelUp
+      when Gosu::MS_WHEEL_UP
         redirect_mouse_wheel(:up)
-      when Gosu::MsWheelDown
+      when Gosu::MS_WHEEL_DOWN
         redirect_mouse_wheel(:down)
       end
 
diff --git a/lib/cyberarm_engine/ui/style.rb b/lib/cyberarm_engine/ui/style.rb
index 279806d..2cfe3bc 100644
--- a/lib/cyberarm_engine/ui/style.rb
+++ b/lib/cyberarm_engine/ui/style.rb
@@ -20,7 +20,8 @@ module CyberarmEngine
     attr_reader :hash
 
     def initialize(hash = {})
-      h = Marshal.load(Marshal.dump(hash))
+      h = hash
+      # h = Marshal.load(Marshal.dump(hash))
 
       h[:default] = {}
 
diff --git a/lib/cyberarm_engine/window.rb b/lib/cyberarm_engine/window.rb
index 9c59824..f76833e 100644
--- a/lib/cyberarm_engine/window.rb
+++ b/lib/cyberarm_engine/window.rb
@@ -37,13 +37,16 @@ module CyberarmEngine
 
       @last_frame_time = Gosu.milliseconds - 1
       @current_frame_time = Gosu.milliseconds
-      self.caption = "CyberarmEngine #{CyberarmEngine::VERSION} #{Gosu.language}"
+      self.caption = "CyberarmEngine #{CyberarmEngine::VERSION} #{Gosu.user_languages.join(', ')}"
 
       @states = []
       @exit_on_opengl_error = false
       preload_default_shaders if respond_to?(:preload_default_shaders)
 
-      setup if defined?(setup)
+      setup
+    end
+
+    def setup
     end
 
     def draw
@@ -120,7 +123,7 @@ module CyberarmEngine
     def push_state(klass, options = {})
       options = { setup: true }.merge(options)
 
-      if klass.instance_of?(klass.class) && defined?(klass.options)
+      if klass.instance_of?(klass.class) && klass.respond_to?(:options)
         @states << klass
         klass.setup if options[:setup]
         klass.post_setup if options[:setup]
diff --git a/mrbgem.rake b/mrbgem.rake
new file mode 100644
index 0000000..acd6a99
--- /dev/null
+++ b/mrbgem.rake
@@ -0,0 +1,29 @@
+MRuby::Gem::Specification.new("mruby-cyberarm_engine") do |spec|
+  spec.license = "MIT"
+  spec.authors = "cyberarm"
+  spec.summary = " Yet another framework for building games with Gosu"
+
+  lib_rbfiles = []
+  # Dir.glob("#{File.expand_path("..", __FILE__)}/lib/**/*.rb").reject do |f|
+    # File.basename(f.downcase, ".rb") == "cyberarm_engine" ||
+    # File.basename(f.downcase, ".rb") == "opengl" ||
+    # f.downcase.include?("/opengl/")
+  # end.reverse!
+
+  local_path = File.expand_path("..", __FILE__)
+  File.read("#{local_path}/lib/cyberarm_engine.rb").each_line do |line|
+    line = line.strip
+
+    next unless line.start_with?("require_relative")
+
+    file = line.split("require_relative").last.strip.gsub("\"", "")
+
+    next if file.include?(" if ")
+
+    lib_rbfiles << "#{local_path}/lib/#{file}.rb"
+  end
+
+  pp lib_rbfiles
+
+  spec.rbfiles = lib_rbfiles
+end