diff --git a/TODO.txt b/TODO.txt
deleted file mode 100644
index 4c55b6f..0000000
--- a/TODO.txt
+++ /dev/null
@@ -1,19 +0,0 @@
-# TODOs
-
-[x] add nineslice drawcmd functions
- [x] draw_*
- [x] exec_*
-
-[ ] add text rendering
- [x] loading fonts
- [x] managing font style
- [x] rendering fonts to surface to texture
- [x] correctly scaling fonts
- [ ] cache rendered text
-
-[ ] add imgui
- [ ] ui windows
- [ ] input fields
- [ ] buttons
- [ ] radios
- [ ] multibox
diff --git a/button.png b/button.png
deleted file mode 100644
index 99c7158..0000000
Binary files a/button.png and /dev/null differ
diff --git a/player.png b/player.png
deleted file mode 100644
index 72cff48..0000000
Binary files a/player.png and /dev/null differ
diff --git a/src/world.c b/src/corelib/world.c
similarity index 100%
rename from src/world.c
rename to src/corelib/world.c
diff --git a/src/world.h b/src/corelib/world.h
similarity index 100%
rename from src/world.h
rename to src/corelib/world.h
diff --git a/src/engine.c b/src/engine.c
index bdf201a..d3b6e14 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -1,4 +1,5 @@
 #include "engine.h"
+#include "world.h"
 #include "corelib/assets.h"
 #include "corelib/render.h"
 #include "corelib/input.h"
@@ -47,7 +48,8 @@ int _engine_run() {
 		.running = 1,
 	};
 
-	load_game();
+	input_init();
+	world_clear();
 	start_game();
 	
 	timespec_get(&start_last_frame, TIME_UTC);
@@ -58,10 +60,13 @@ int _engine_run() {
 		if(next_time.tv_nsec < start_last_frame.tv_nsec) _delta_time = 0;
 		start_last_frame = next_time;
 		_handle_events();
+		update_input();
 		_render_mode = 1;
 		update_ui();
 		_render_mode = 0;
+		update_objects();	// update world objects
 		update_game();
+		draw_objects();		// draw world objects
 		swap_buffer();
 	}
 	return 0;
diff --git a/src/engine.h b/src/engine.h
index ada21c4..87bf672 100644
--- a/src/engine.h
+++ b/src/engine.h
@@ -9,11 +9,10 @@ extern float delta_time();
 
 /* TO BE DEFINED IN GAME */
 
-extern void load_game();
-extern void game_exit();
 extern void start_game();
 extern void update_game();
 extern void update_ui();
+extern void game_exit();
 
 #ifdef __cplusplus
 }
diff --git a/src/game.c b/src/game.c
index c2feec3..95016d2 100644
--- a/src/game.c
+++ b/src/game.c
@@ -1,6 +1,5 @@
 #include "engine.h"
 #include "world.h"
-#include "player.h"
 #include "corelib/input.h"
 #include "corelib/render.h"
 #include "corelib/assets.h"
@@ -8,83 +7,45 @@
 #include "SDL2/SDL_mouse.h"
 #include "SDL2/SDL_scancode.h"
 
-int dragging = 0;
-int drawing = 0;
-spritesheet_t world_sheet;
-
 void on_quit_key(int down) {
+	// Q is pressed or released
 	if(down) {
+		// stop running when Q is pressed
 		g_context.running = 0;
 	}
 }
 
+void on_horizontal(int axis) {
+	// when A or D is pressed or released
+}
+
+void on_vertical(int axis) {
+	// W or S is pressed or released
+}
+
 void on_click(int down) {
-	drawing = down;
-}
-
-void on_erase(int down) {
-	drawing = -down;
-}
-
-void on_drag_world(float dx, float dy) {
-	if(dragging) {
-		g_active_view.x -= dx * g_active_view.width;
-		g_active_view.y -= dy * g_active_view.width;
-	}
-}
-
-void on_middle_mouse(int down) {
-	dragging = down;
-}
-
-void on_debug_frame(int down) {
-	if(down) {
-		d_debug_next_frame = 1;
-	}
-}
-
-
-void on_button_zoom(int axis) {
-	if(axis != 0) {
-		g_active_view.width += axis;
-	}
-}
-
-void on_scroll_zoom(float delta) {
-	g_active_view.width -= delta * 0.5f;
-}
-
-void load_game() {
-	world_sheet = make_spritesheet("tileset.png", 189, 189);
-
-	input_init();
-	world_clear();
-	add_key_listener(SDL_SCANCODE_UNKNOWN, SDL_SCANCODE_Q, &on_quit_key);
-	add_key_listener(SDL_SCANCODE_UNKNOWN, SDL_SCANCODE_TAB, &on_debug_frame);
-	add_key_listener(SDL_SCANCODE_MINUS, SDL_SCANCODE_EQUALS, &on_button_zoom);
-	add_mouse_button_listener(SDL_BUTTON_LMASK, &on_click);
-	add_mouse_button_listener(SDL_BUTTON_RMASK, &on_erase);
-	add_mouse_button_listener(SDL_BUTTON_MMASK, &on_middle_mouse);
-	add_mouse_listener(&on_drag_world);
-	add_scroll_listener(&on_scroll_zoom);
-
-	create_player();
+	// when the left mouse button is pressed down
+	// float mouse_x, mouse_y;
+	// mouse_world_position(&mouse_x, &mouse_y);
 }
 
 void start_game() {
+	// called when the game first run
 	g_active_view.width = 21;
+	add_key_listener(SDL_SCANCODE_UNKNOWN, SDL_SCANCODE_Q, &on_quit_key);
+	add_key_listener(SDL_SCANCODE_S, SDL_SCANCODE_W, &on_horizontal);
+	add_key_listener(SDL_SCANCODE_A, SDL_SCANCODE_D, &on_vertical);
+	add_mouse_button_listener(SDL_BUTTON_LMASK, &on_click);
 }
 
 void update_game() {
-	if(drawing == 1) {
-		drawing = 2;
-	}
-	update_objects();
-	draw_objects();
+	// called every frame,
+	// render calls made in this function will be in *world* space
 }
 
 void update_ui() {
-	update_input();
+	// called every frame,
+	// render calls made in this function will be in *screen* space
 }
 
 void game_exit() {}
diff --git a/src/player.c b/src/player.c
deleted file mode 100644
index 4fada2e..0000000
--- a/src/player.c
+++ /dev/null
@@ -1,41 +0,0 @@
-#include "player.h"
-#include "layers.h"
-#include "world.h"
-#include "input.h"
-#include "engine.h"
-#include <SDL2/SDL_scancode.h>
-
-float player_move_x = 0;
-float player_move_y = 0;
-float player_xv = 0;
-float player_yv = 0;
-object_t* player_instance = NULL;
-
-void player_update(object_t *object) {
-	float m = sqrtf(player_move_x*player_move_x + player_move_y*player_move_y);
-	if(m == FP_NAN) m = 1;
-	m = 1.f/m;
-	player_xv = player_move_x * 3.f * m,
-	player_yv = player_move_y * 3.f * m;
-	object->sprite.x += player_xv * delta_time();
-	object->sprite.y += player_yv * delta_time();
-}
-
-object_t* create_player() {
-	player_instance = make_object();
-	player_instance->evt_update = &player_update;
-	player_instance->sprite = make_sprite("player.png", 0, 0);
-
-	add_key_listener(SDL_SCANCODE_A, SDL_SCANCODE_D, &player_axis_horizontal);
-	add_key_listener(SDL_SCANCODE_S, SDL_SCANCODE_W, &player_axis_vertical);
-
-	return player_instance;
-}
-
-void player_axis_horizontal(int axis) {
-	player_move_x = axis;
-}
-
-void player_axis_vertical(int axis) {
-	player_move_y = -axis;
-}
diff --git a/src/player.h b/src/player.h
deleted file mode 100644
index 3f116e9..0000000
--- a/src/player.h
+++ /dev/null
@@ -1,16 +0,0 @@
-#ifndef _player_h
-#define _player_h
-
-struct object_t;
-
-extern float player_move_x, player_move_y,
-			 player_xv, player_yv;
-extern struct object_t* player_instance;
-
-void player_update(struct object_t* object);
-struct object_t* create_player();
-
-extern void player_axis_horizontal(int axis);
-extern void player_axis_vertical(int axis);
-
-#endif /* _player_h */
diff --git a/tileset.png b/tileset.png
deleted file mode 100644
index 9c774d9..0000000
Binary files a/tileset.png and /dev/null differ
diff --git a/ui_font.otf b/ui_font.otf
deleted file mode 100644
index 5e87de2..0000000
Binary files a/ui_font.otf and /dev/null differ