idk if this is the way to do this but it moves!

main.c

@@ -56,16 +56,34 @@ int is_held(char k)
 	return 0;
 }
 
+static int player_x = 100;
+static int player_y = 100;
+static float player_vx = 0.0;
+static float player_vy = 0.0;
+static float player_ax = 0.0;
+static float player_ay = 0.0;
+
 void key_down(char k)
 {
 	add_keydown(k);
 	printf("%c pressed!\n", k);
+	switch (k)
+	{
+		case 'a': player_ax = -1; break;
+		case 'd': player_ax = 1; break;
+		case 0x20: /*jump();*/ break;
+	}
 }
 
 void key_up(char k)
 {
 	remove_keydown(k);
 	printf("%c un-pressed\n", k);
+	switch (k)
+	{
+		case 'a': player_ax = 0; break;
+		case 'd': player_ax = 0; break;
+	}
 }
 
 static int mousex = 0;
@@ -102,6 +120,32 @@ void process_input(void)
 	else if (e->type == MOUSEUP)	mouse_up(e->mouse_button);
 }
 
+void erase_entity(/*struct entity*/)
+{
+	/* get sprite info, etc */
+	/* FIXME */
+	cat_fill(1, 0, player_x, player_y, 50, 50, 0, 0, 0);
+}
+
+void draw_entity(/* struct entity */)
+{
+	/* get sprite info, etc */
+	/* FIXME */
+	cat_fill(1, 1, player_x, player_y, 50, 50, 115, 72, 6);
+}
+
+void erase_entities(void)
+{
+	/* TODO more than just player entity */
+	erase_entity(/*player*/);
+}
+
+void draw_entities(void)
+{
+	/* TODO more than just player entity */
+	draw_entity(/*player*/);
+}
+
 static long last_sec = 0;
 static long last_nsec = 0;
 
@@ -116,17 +160,24 @@ void tick(void)
 	else if ((t.tv_sec - last_sec) > 0) goto yes;
 	else if ((t.tv_nsec - last_nsec) > NS_PER_TICK) goto yes;
 	else return;
+	/* do a tick */
 	yes:	last_sec = t.tv_sec;
 		last_nsec = t.tv_nsec;
 
 	/* code to run every tick goes here */
+	erase_entities();
+	player_vx += player_ax;
+	player_vy += player_ay;
+	player_x += (int)player_vx;
+	player_y += (int)player_vy;
+	draw_entities();
 }
 
 void game_loop(void)
 {
+	cat_render();
 	process_input();
 	tick();
-	cat_render();
 }
 
 int main(int argc, char** argv)
@@ -134,6 +185,7 @@ int main(int argc, char** argv)
 	cat_init();
 	cat_create_window(1920, 1080);
 	cat_play_wav("etc/example.wav");
+		/* layer, visibility, x, y, width, height, r, g, b */
 	cat_fill(0, 1, 0, 0, screen_width - 1, screen_height - 1, 132, 155, 132);
 	while (1) game_loop();
 	return 0;