diff --git a/shell/parse-controls.sml b/shell/parse-controls.sml
index 3e5beda..e36ae1f 100644
--- a/shell/parse-controls.sml
+++ b/shell/parse-controls.sml
@@ -1 +1,154 @@
-structure ParseControls = struct end
+structure ParseControls =
+struct
+  datatype action =
+    ACTION_LEFT
+  | ACTION_RIGHT
+  | ACTION_UP
+  | ACTION_DOWN
+  | ACTION_JUMP
+  | ACTION_ATTACK
+
+  fun actionFromString str =
+    case str of
+      "ACTION_LEFT" => SOME ACTION_LEFT
+    | "ACTION_RIGHT" => SOME ACTION_RIGHT
+    | "ACTION_UP" => SOME ACTION_UP
+    | "ACTION_DOWN" => SOME ACTION_DOWN
+    | "ACTTION_JUMP" => SOME ACTION_JUMP
+    | "ACTION_ATTACK" => SOME ACTION_ATTACK
+    | _ => NONE
+
+  fun findColon (pos, str) =
+    if pos = String.size str then
+      ~1
+    else
+      let val chr = String.sub (str, pos)
+      in if chr = #":" then pos else findColon (pos + 1, str)
+      end
+
+  type parsed_keys =
+    { left: CoreKey.key_code option
+    , right: CoreKey.key_code option
+    , up: CoreKey.key_code option
+    , down: CoreKey.key_code option
+    , jump: CoreKey.key_code option
+    , attack: CoreKey.key_code option
+    }
+
+  fun updateControls (action, key, controls: parsed_keys) =
+    let
+      val {left, right, up, down, jump, attack} = controls
+    in
+      case action of
+        ACTION_LEFT =>
+          { left = SOME key
+          , right = right
+          , up = up
+          , down = down
+          , jump = jump
+          , attack = attack
+          }
+      | ACTION_RIGHT =>
+          { left = left
+          , right = SOME key
+          , up = up
+          , down = down
+          , jump = jump
+          , attack = attack
+          }
+      | ACTION_UP =>
+          { left = left
+          , right = right
+          , up = SOME key
+          , down = down
+          , jump = jump
+          , attack = attack
+          }
+      | ACTION_DOWN =>
+          { left = left
+          , right = right
+          , up = up
+          , down = SOME key
+          , jump = jump
+          , attack = attack
+          }
+      | ACTION_JUMP =>
+          { left = left
+          , right = right
+          , up = up
+          , down = down
+          , jump = SOME key
+          , attack = attack
+          }
+      | ACTION_ATTACK =>
+          { left = left
+          , right = right
+          , up = up
+          , down = down
+          , jump = jump
+          , attack = SOME key
+          }
+    end
+
+  fun returnControls controls =
+    let
+      val {left, right, up, down, jump, attack} = controls
+    in
+      case (left, right, up, down, jump, attack) of
+        (SOME left, SOME right, SOME up, SOME down, SOME jump, SOME attack) =>
+          SOME
+            { left = left
+            , right = right
+            , up = up
+            , down = down
+            , jump = jump
+            , attack = attack
+            }
+      | _ => NONE
+    end
+
+  fun helpParse (controls, io) =
+    case TextIO.inputLine io of
+      SOME line =>
+        let
+          val colon = findColon (0, line)
+        in
+          if colon = ~1 then
+            helpParse (controls, io)
+          else
+            let
+              val actionStart = colon + 1
+              val actionLength = String.size line - actionStart
+              val actionString =
+                String.substring (line, actionStart, actionLength)
+              val action = actionFromString actionString
+
+              val keyString = String.substring (line, 0, colon)
+              val key = CoreKey.keyFromString keyString
+
+              val controls =
+                (case (action, key) of
+                   (SOME action, SOME key) =>
+                     updateControls (action, key, controls)
+                 | (_, _) => controls)
+            in
+              helpParse (controls, io)
+            end
+        end
+    | NONE => returnControls controls
+
+  fun parse () =
+    let
+      val initial =
+        { left = NONE
+        , right = NONE
+        , up = NONE
+        , down = NONE
+        , jump = NONE
+        , attack = NONE
+        }
+      val io = TextIO.openIn "controls.config"
+    in
+      helpParse (initial, io)
+    end
+end