Put this into /etc/xdg/awesome/rc.lua and /usr/share/awesome/themes/default/empty.lua for a maximized window completely without menues and decorators. :)

empty.lua

---------------------------
-- Default awesome theme --
---------------------------

theme = {}

theme.font          = "sans 8"

theme.bg_normal     = "#222222"
theme.bg_focus      = "#535d6c"
theme.bg_urgent     = "#ff0000"
theme.bg_minimize   = "#444444"

theme.fg_normal     = "#aaaaaa"
theme.fg_focus      = "#ffffff"
theme.fg_urgent     = "#ffffff"
theme.fg_minimize   = "#ffffff"

theme.border_width  = "1"
theme.border_normal = "#000000"
theme.border_focus  = "#535d6c"
theme.border_marked = "#91231c"

-- There are other variable sets
-- overriding the default one when
-- defined, the sets are:
-- [taglist|tasklist]_[bg|fg]_[focus|urgent]
-- titlebar_[bg|fg]_[normal|focus]
-- tooltip_[font|opacity|fg_color|bg_color|border_width|border_color]
-- mouse_finder_[color|timeout|animate_timeout|radius|factor]
-- Example:
--theme.taglist_bg_focus = "#ff0000"

-- Display the taglist squares
theme.taglist_squares_sel   = "/usr/share/awesome/themes/default/taglist/squarefw.png"
theme.taglist_squares_unsel = "/usr/share/awesome/themes/default/taglist/squarew.png"

theme.tasklist_floating_icon = "/usr/share/awesome/themes/default/tasklist/floatingw.png"

-- Variables set for theming the menu:
-- menu_[bg|fg]_[normal|focus]
-- menu_[border_color|border_width]
theme.menu_submenu_icon = "/usr/share/awesome/themes/default/submenu.png"
theme.menu_height = "15"
theme.menu_width  = "100"

-- You can add as many variables as
-- you wish and access them by using
-- beautiful.variable in your rc.lua
--theme.bg_widget = "#cc0000"

-- Define the image to load
theme.titlebar_close_button_normal = "/usr/share/awesome/themes/default/titlebar/close_normal.png"
theme.titlebar_close_button_focus  = "/usr/share/awesome/themes/default/titlebar/close_focus.png"

theme.titlebar_ontop_button_normal_inactive = "/usr/share/awesome/themes/default/titlebar/ontop_normal_inactive.png"
theme.titlebar_ontop_button_focus_inactive  = "/usr/share/awesome/themes/default/titlebar/ontop_focus_inactive.png"
theme.titlebar_ontop_button_normal_active = "/usr/share/awesome/themes/default/titlebar/ontop_normal_active.png"
theme.titlebar_ontop_button_focus_active  = "/usr/share/awesome/themes/default/titlebar/ontop_focus_active.png"

theme.titlebar_sticky_button_normal_inactive = "/usr/share/awesome/themes/default/titlebar/sticky_normal_inactive.png"
theme.titlebar_sticky_button_focus_inactive  = "/usr/share/awesome/themes/default/titlebar/sticky_focus_inactive.png"
theme.titlebar_sticky_button_normal_active = "/usr/share/awesome/themes/default/titlebar/sticky_normal_active.png"
theme.titlebar_sticky_button_focus_active  = "/usr/share/awesome/themes/default/titlebar/sticky_focus_active.png"

theme.titlebar_floating_button_normal_inactive = "/usr/share/awesome/themes/default/titlebar/floating_normal_inactive.png"
theme.titlebar_floating_button_focus_inactive  = "/usr/share/awesome/themes/default/titlebar/floating_focus_inactive.png"
theme.titlebar_floating_button_normal_active = "/usr/share/awesome/themes/default/titlebar/floating_normal_active.png"
theme.titlebar_floating_button_focus_active  = "/usr/share/awesome/themes/default/titlebar/floating_focus_active.png"

theme.titlebar_maximized_button_normal_inactive = "/usr/share/awesome/themes/default/titlebar/maximized_normal_inactive.png"
theme.titlebar_maximized_button_focus_inactive  = "/usr/share/awesome/themes/default/titlebar/maximized_focus_inactive.png"
theme.titlebar_maximized_button_normal_active = "/usr/share/awesome/themes/default/titlebar/maximized_normal_active.png"
theme.titlebar_maximized_button_focus_active  = "/usr/share/awesome/themes/default/titlebar/maximized_focus_active.png"

-- You can use your own command to set your wallpaper
theme.wallpaper_cmd = { nil }

-- You can use your own layout icons like this:
theme.layout_fairh = "/usr/share/awesome/themes/default/layouts/fairhw.png"
theme.layout_fairv = "/usr/share/awesome/themes/default/layouts/fairvw.png"
theme.layout_floating  = "/usr/share/awesome/themes/default/layouts/floatingw.png"
theme.layout_magnifier = "/usr/share/awesome/themes/default/layouts/magnifierw.png"
theme.layout_max = "/usr/share/awesome/themes/default/layouts/maxw.png"
theme.layout_fullscreen = "/usr/share/awesome/themes/default/layouts/fullscreenw.png"
theme.layout_tilebottom = "/usr/share/awesome/themes/default/layouts/tilebottomw.png"
theme.layout_tileleft   = "/usr/share/awesome/themes/default/layouts/tileleftw.png"
theme.layout_tile = "/usr/share/awesome/themes/default/layouts/tilew.png"
theme.layout_tiletop = "/usr/share/awesome/themes/default/layouts/tiletopw.png"
theme.layout_spiral  = "/usr/share/awesome/themes/default/layouts/spiralw.png"
theme.layout_dwindle = "/usr/share/awesome/themes/default/layouts/dwindlew.png"

theme.awesome_icon = "/usr/share/awesome/icons/awesome16.png"

return theme
-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=80

rc.lua

-- Standard awesome library
require("awful")
require("awful.autofocus")
require("awful.rules")
-- Theme handling library
require("beautiful")
-- Notification library
require("naughty")

-- Load Debian menu entries
require("debian.menu")

-- {{{ Error handling
-- Check if awesome encountered an error during startup and fell back to
-- another config (This code will only ever execute for the fallback config)
if awesome.startup_errors then
    naughty.notify({ preset = naughty.config.presets.critical,
                     title = "Oops, there were errors during startup!",
                     text = awesome.startup_errors })
end

-- Handle runtime errors after startup
do
    local in_error = false
    awesome.add_signal("debug::error", function (err)
        -- Make sure we don't go into an endless error loop
        if in_error then return end
        in_error = true

        naughty.notify({ preset = naughty.config.presets.critical,
                         title = "Oops, an error happened!",
                         text = err })
        in_error = false
    end)
end
-- }}}

-- {{{ Variable definitions
-- Themes define colours, icons, and wallpapers

-- beautiful.init("/usr/share/awesome/themes/default/theme.lua")
beautiful.init("/usr/share/awesome/themes/default/empty.lua")

-- Table of layouts to cover with awful.layout.inc, order matters.
layouts =
 {
     awful.layout.suit.floating,
     awful.layout.suit.tile,
     awful.layout.suit.tile.left,
     awful.layout.suit.tile.bottom,
     awful.layout.suit.tile.top,
     awful.layout.suit.fair,
     awful.layout.suit.fair.horizontal,
     awful.layout.suit.spiral,
     awful.layout.suit.spiral.dwindle,
     awful.layout.suit.max,
     awful.layout.suit.max.fullscreen,
     awful.layout.suit.magnifier
 }
-- }}}

-- {{{ Tags
-- Define a tag table which hold all screen tags.
 tags = {}
 for s = 1, screen.count() do
     -- Each screen has its own tag table.
     tags[s] = awful.tag({ 1 }, s, layouts[1])
 end
-- }}}


-- }}}


-- {{{ Rules
awful.rules.rules = {
    -- All clients will match this rule.
    { rule = { },
      properties = { border_width = 0,
                     border_color = beautiful.border_normal,
                     focus = true,
                     floating = false,
                     keys = clientkeys,
                     maximized_vertical = true,
                     maximized_horizontal = true,
                     buttons = clientbuttons } }
}
-- }}}

-- {{{ Signals
-- Signal function to execute when a new client appears.
client.add_signal("manage", function (c, startup)
    -- Add a titlebar
    -- awful.titlebar.add(c, { modkey = modkey })

    -- Enable sloppy focus
    c:add_signal("mouse::enter", function(c)
        if awful.layout.get(c.screen) ~= awful.layout.suit.magnifier
            and awful.client.focus.filter(c) then
            client.focus = c
        end
    end)

    if not startup then
        -- Set the windows at the slave,
        -- i.e. put it at the end of others instead of setting it master.
        -- awful.client.setslave(c)

        -- Put windows in a smart way, only if they does not set an initial position.
        if not c.size_hints.user_position and not c.size_hints.program_position then
            awful.placement.no_overlap(c)
            awful.placement.no_offscreen(c)
        end
    end
end)

client.add_signal("focus", function(c) c.border_color = beautiful.border_focus end)
client.add_signal("unfocus", function(c) c.border_color = beautiful.border_normal end)
-- }}}