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+Project & game architecture
+---------------------------
+
+The different source files in the project is divided into several source files
+within the `src` directory of this repository with a (somewhat) corresponding
+name.
+
+## State Management [state.c](../src/state.c)
+
+![gamestate illustration](gamestate.svg)
+![gameloop illustration](gameloop.svg)
+
+WIP
+
+```
+while((newstate = state_update(current_state)) != STATE_Exit) {
+  if (newstate != STATE_NULL) {
+    state = newstate;
+    state_free(current_state);
+    current_state = state_load(newstate);
+  } else {
+    // Input stuff
+    // Update stuff
+    // Render stuff
+    // Time stuff
+  }
+}
+```
+
+
+## Input Handling [keypress.h](../src/keypress.h)
+
+We use a null-terminated statically allocated list of structs containing the
+following:
+* `struct Key`: Takes a `uint16 modifier` and a `uint32 key`
+  ([SDL Keycode](https://wiki.libsdl.org/SDLKeycodeLookup))
+* `uint32 time_pressed`: Time in ms since it was pressed.
+* `void (*down_function)(void*)`: The function to be run upon key activation.
+* `struct Funarg down_arg`: The argument for the function to be called.  The argument is
+  automatically added a pointer to the current (game) context for each call.
+* `void (*up_function)(void*)`: The function to be run upon key deactivation.
+* `struct Funarg up_arg`: The argument for the function to be called.
+
+Upon keypress,
+```c
+for (int i = 0; i < len(keys) && keys[i] != NULL; i++) {
+  if ( keys[i].function_down != NULL
+    && keys[i].key.key == pressed_key
+    && keys[i].key.modifier & current_mods == current_mods) {
+
+      time_pressed = now();
+      keys[i].function_down(funarg_up);
+
+    }
+}
+```
+And basically the same goes for keyup, except, we dont check any modifier keys,
+instead we check if `time_pressed > 0`
+
+By using `time_pressed`, we can "charge" moves if needed be, and once released
+we can measure how long the player held down the key.
+It can be visualized by giving a pointer to a UI-part and setting it to visible,
+and toggling said visibility again once the key is released.
+
+## Rendering
+
+### Tile rendering
+
+When rendering tiles, we go by drawing walls on the floor tile, such that for
+each floor tile we calculate the number of adjacent walls and fetch the
+corresponding texture that match that combination of neighbouring walls.