diff --git a/main.lua b/main.lua
index c907c12..356d22e 100644
--- a/main.lua
+++ b/main.lua
@@ -94,7 +94,7 @@ function main_action(self)
 end
 
 function main_scene(do_backdrop, do_logo)
-    local group = am.group():tag"main_scene"
+    local group = am.group()
 
     if do_backdrop then
         local map = hex_hexagonal_map(30)
@@ -173,7 +173,6 @@ function main_scene(do_backdrop, do_logo)
         {
             texture = TEXTURES.MAP_EDITOR_HEX,
             action = function()
-                win.scene:remove("main_scene")
                 map_editor_init()
             end
         },
diff --git a/src/extra.lua b/src/extra.lua
deleted file mode 100644
index 2822d97..0000000
--- a/src/extra.lua
+++ /dev/null
@@ -1,89 +0,0 @@
-
--- utility functions that don't below elsewhere go here,
--- especially if they would be at home on the global 'math' or 'table' variables, or are otherwise extensions of standard lua features
--- try to avoid *too* much amulet specific stuff, but vector types are probably ok.
-
-function fprofile(f, ...)
-    local t1 = am.current_time()
-    local result = { f(...) }
-    local time = am.current_time() - t1
-    --log("%f", time)
-    return time, unpack(result)
-end
-
-function math.wrapf(float, range)
-    return float - range * math.floor(float / range)
-end
-
-function math.lerp(v1, v2, t)
-    return v1 * t + v2 * (1 - t)
-end
-
--- don't use this with sparse arrays
-function table.rchoice(t)
-    return t[math.floor(math.random() * #t) + 1]
-end
-
-function table.count(t)
-    local count = 0
-    for i,v in pairs(t) do
-        if v ~= nil then
-            count = count + 1
-        end
-    end
-    return count
-end
-
-function table.highest_index(t)
-    local highest = nil
-    for i,v in pairs(t) do
-        if i and not highest then
-            highest = i
-        end
-
-        if i > highest then
-            highest = i
-        end
-    end
-    return highest
-end
-
-function table.find(t, predicate)
-    for i,v in pairs(t) do
-        if predicate(v) then
-            return i,v
-        end
-    end
-    return nil
-end
-
-function quicksort(t, low_index, high_index, comparator)
-    local function partition(t, low_index, high_index)
-        local i = low_index - 1
-        local pivot = t[high_index]
-
-        for j = low_index, high_index - 1 do
-            if comparator(t[j], t[pivot]) <= 0 then
-                i = i + 1
-                t[i], t[j] = t[j], t[i]
-            end
-        end
-
-        t[i + 1], t[high_index] = t[high_index], t[i + 1]
-        return i + 1
-    end
-
-    if #t == 1 then
-        return t
-    end
-
-    if comparator(t[low_index], t[high_index]) < 0 then
-        local partition_index = partition(t, low_index, high_index)
-
-        quicksort(t, low_index, partition_index - 1, comparator)
-        quicksort(t, partition_index + 1, high_index, comparator)
-    end
-
-    return t
-end
-
diff --git a/src/geometry.lua b/src/geometry.lua
deleted file mode 100644
index ede2bea..0000000
--- a/src/geometry.lua
+++ /dev/null
@@ -1,23 +0,0 @@
-
-function circles_intersect(center1, center2, radius1, radius2)
-    local c1, c2, r1, r2 = center1, center2, radius1, radius2
-    local d = math.distance(center1, center2)
-    local radii_sum = r1 + r2
-                                    -- touching
-    if d == radii_sum then          return 1
-
-                                    -- not touching or intersecting
-    elseif d > radii_sum then       return false
-
-                                    -- intersecting
-    else                            return 2
-    end
-end
-
-function point_in_rect(point, rect)
-    return point.x > rect.x1
-       and point.x < rect.x2
-       and point.y > rect.y1
-       and point.y < rect.y2
-end
-
diff --git a/src/gui.lua b/src/gui.lua
deleted file mode 100644
index 81f8a0f..0000000
--- a/src/gui.lua
+++ /dev/null
@@ -1,162 +0,0 @@
-
--- text popup in the middle of the screen that dissapates
-function gui_alert(message, color, decay_time)
-    win.scene:append(
-        am.scale(3) ^ am.text(message, color or COLORS.WHITE)
-        :action(coroutine.create(function(self)
-            am.wait(am.tween(self, decay_time or 1, { color = vec4(0) }, am.ease_in_out))
-            win.scene:remove(self)
-        end))
-    )
-end
-
-function gui_numberfield(dimensions, opts)
-
-end
-
-function gui_textfield(position, dimensions, max, disallowed_chars)
-    local width, height = dimensions.x, dimensions.y
-    local disallowed_chars = disallowed_chars or {}
-    local max = max or 10
-
-    local outer_rect = am.rect(
-        -width/2,
-        -height/2,
-        width/2,
-        height/2,
-        COLORS.VERY_DARK_GRAY
-    )
-    local inner_rect = am.rect(
-        -width/2 + 1,
-        -height/2 + 1,
-        width/2 - 2,
-        height/2 - 2,
-        COLORS.PALE_SILVER
-    )
-
-    local group = am.group{
-        outer_rect,
-        inner_rect,
-        am.translate(-width/2 + 5, 0) ^ am.scale(2) ^ am.text("", COLORS.BLACK, "left"),
-        am.translate(-width/2 + 5, -8) ^ am.line(vec2(0, 0), vec2(16, 0), 2, COLORS.BLACK)
-    }
-
-    group:action(function(self)
-        local keys = win:keys_pressed()
-        if #keys == 0 then return end
-
-        local chars = {}
-        local shift = win:key_down("lshift") or win:key_down("rshift")
-        for i,k in pairs(keys) do
-            if k:len() == 1 then -- @HACK alphabetical or digit characters
-                if string.match(k, "%a") then
-                    if shift then
-                        table.insert(chars, k:upper())
-                    else
-                        table.insert(chars, k)
-                    end
-                elseif string.match(k, "%d") then
-                    if shift then
-                        if k == "1" then table.insert(chars, "!")
-                        elseif k == "2" then table.insert(chars, "@")
-                        elseif k == "3" then table.insert(chars, "#")
-                        elseif k == "4" then table.insert(chars, "$")
-                        elseif k == "5" then table.insert(chars, "%")
-                        elseif k == "6" then table.insert(chars, "^")
-                        elseif k == "7" then table.insert(chars, "&")
-                        elseif k == "8" then table.insert(chars, "*")
-                        elseif k == "9" then table.insert(chars, "(")
-                        elseif k == "0" then table.insert(chars, ")")
-                        end
-                    else
-                        table.insert(chars, k)
-                    end
-                end
-            -- begin non-alphabetical/digit
-            elseif k == "minus" then
-                if shift then table.insert(chars, "_")
-                else          table.insert(chars, "-") end
-            elseif k == "equals" then
-                if shift then table.insert(chars, "=")
-                else          table.insert(chars, "+") end
-            elseif k == "leftbracket" then
-                if shift then table.insert(chars, "{")
-                else          table.insert(chars, "[") end
-            elseif k == "rightbracket" then
-                if shift then table.insert(chars, "}")
-                else          table.insert(chars, "]") end
-            elseif k == "backslash" then
-                if shift then table.insert(chars, "|")
-                else          table.insert(chars, "\\") end
-            elseif k == "semicolon" then
-                if shift then table.insert(chars, ":")
-                else          table.insert(chars, ";") end
-            elseif k == "quote" then
-                if shift then table.insert(chars, "\"")
-                else          table.insert(chars, "'") end
-            elseif k == "backquote" then
-                if shift then table.insert(chars, "~")
-                else          table.insert(chars, "`") end
-            elseif k == "comma" then
-                if shift then table.insert(chars, "<")
-                else          table.insert(chars, ",") end
-            elseif k == "period" then
-                if shift then table.insert(chars, ">")
-                else          table.insert(chars, ".") end
-            elseif k == "slash" then
-                if shift then table.insert(chars, "?")
-                else          table.insert(chars, "/") end
-
-            -- control characters
-            elseif k == "backspace" then
-                -- @NOTE this doesn't preserve the order of chars in the array so if
-                -- someone presses a the key "a" then the backspace key in the same frame, in that order
-                -- the backspace occurs first
-                self"text".text = self"text".text:sub(1, self"text".text:len() - 1)
-
-            elseif k == "tab" then
-                -- @TODO
-
-            elseif k == "space" then
-                table.insert(chars, " ")
-
-            elseif k == "capslock" then
-                -- @OTOD
-            end
-        end
-
-        for _,c in pairs(chars) do
-            if not disallowed_chars[c] then
-                if self"text".text:len() <= max then
-                    self"text".text = self"text".text .. c
-                end
-            end
-        end
-    end)
-
-    return group
-end
-
-function gui_slider(position, dimensions, bar_color, circle_color, min, max, default_value, action)
-    local position = position or vec2(0)
-    local width = dimensions.x
-    local height = dimensions.y
-    local bar_color = bar_color or COLORS.WHITE
-    local circle_color = circle_color or COLORS.GREEN_YELLOW
-    local min = min or 0
-    local max = max or 100
-    local default_value = math.clamp(default_value or 50, min, max)
-
-    local slider = pack_texture_into_sprite(TEXTURES.GUI_SLIDER, width, height, bar_color)
-    local circle = am.circle(vec2(-width/2 + (default_value/max) * (width/2), 0), height, circle_color)
-
-    local node = am.translate(position) ^ am.group{
-        slider,
-        circle
-    }
-
-    if action then node:action(action) end
-
-    return node
-end
-
diff --git a/src/memory.lua b/src/memory.lua
deleted file mode 100644
index 88b92ea..0000000
--- a/src/memory.lua
+++ /dev/null
@@ -1,23 +0,0 @@
-
-local garbage_collector_cycle_timing_history = {}
-local garbage_collector_average_cycle_time = 0
-function run_garbage_collector_cycle()
-    local time, result = fprofile(collectgarbage, "collect")
-
-    table.insert(garbage_collector_cycle_timing_history, time)
-    -- re-calc average gc timing
-    local total = 0
-    for _,v in pairs(garbage_collector_cycle_timing_history) do
-        total = total + v
-    end
-    garbage_collector_average_cycle_time = total / #garbage_collector_cycle_timing_history
-end
-
-function check_if_can_collect_garbage_for_free(frame_start_time, min_fps)
-    -- often this will be polled at the end of a frame to see if we're running fast or slow,
-    -- and if we have some time to kill before the start of the next frame, we could maybe run gc.
-    if (am.current_time() - frame_start_time) < (1 / (min_fps or 60) + garbage_collector_average_cycle_time) then
-        run_garbage_collector_cycle()
-    end
-end
-