diff --git a/Makefile b/Makefile
index 4ef078d..dc9cbbc 100644
--- a/Makefile
+++ b/Makefile
@@ -27,6 +27,8 @@ SRC = src/engine/engine.c \
 	src/utility/my_strcmp.c \
 	src/utility/pow.c \
 	src/utility/read_line.c \
+	src/utility/list.c \
+	src/utility/tupple.c \
 	src/deserializer/deserialize_entity.c \
 	src/deserializer/prefab.c \
 	src/system.c \
diff --git a/include/engine.h b/include/engine.h
index 38c20b9..21e8d12 100644
--- a/include/engine.h
+++ b/include/engine.h
@@ -30,6 +30,7 @@ struct gc_engine
     gc_list *systems;
     void (*add_system)(gc_engine *engine, const gc_system *system);
     const gc_system *(*get_system)(gc_engine *engine, const char *name);
+
     gc_list *components;
     void (*add_component)(gc_engine *engine, const void *component);
     const void *(*get_component)(gc_engine *engine, const char *name);
diff --git a/include/entity.h b/include/entity.h
index 217594d..c9772a6 100644
--- a/include/entity.h
+++ b/include/entity.h
@@ -22,13 +22,11 @@ struct gc_entity
     bool (*has_component)(const gc_entity *entity, const char *name);
     char *(*serialize)(gc_entity *entity, int fd);
     void (*destroy)(gc_entity *entity);
-
-    gc_entity *next;
-    gc_entity *prev;
 };
 
 gc_entity *entity_create(void);
 gc_entity *entity_create_with_id(int id);
-gc_entity *entity_add(gc_entity *list, gc_entity *entity);
+gc_entity *entity_get(gc_scene *scene, int id);
+int entity_add(gc_scene *scene, gc_entity *entity);
 gc_entity *entity_add_component(gc_entity *entity, void *component);
 char *entity_serialize(gc_entity *entity, int fd);
\ No newline at end of file
diff --git a/include/list.h b/include/list.h
index e4ca8c8..d471961 100644
--- a/include/list.h
+++ b/include/list.h
@@ -13,4 +13,6 @@ struct gc_list
 {
     void *data;
     gc_list *next;
-};
\ No newline at end of file
+};
+
+gc_list *list_add(gc_list *list, void *obj);
\ No newline at end of file
diff --git a/include/prefab.h b/include/prefab.h
index 6b84084..1681762 100644
--- a/include/prefab.h
+++ b/include/prefab.h
@@ -9,7 +9,6 @@
 
 #include "entity.h"
 
-gc_entity *prefab_load(gc_engine *engine, const char *path);
-
+int prefab_load(gc_engine *engine, const char *path);
 
 gc_entity *deserialize_entity(gc_engine *engine, node *n);
\ No newline at end of file
diff --git a/include/scene.h b/include/scene.h
index bb4d860..b1ade4d 100644
--- a/include/scene.h
+++ b/include/scene.h
@@ -11,14 +11,20 @@ typedef struct gc_scene gc_scene;
 #include "engine.h"
 #include "entity.h"
 #include "texture.h"
+#include "list.h"
+#include "tupple.h"
 #include <stdbool.h>
 
 struct gc_scene
 {
-    gc_entity *entities;
     gc_texture **textures;
-    int (*add_entity)(gc_scene *scene, gc_entity *entity);
     void (*destroy)(gc_scene *scene);
+
+    gc_list *entities;
+    gc_tupple *entities_by_cmp;
+    int (*add_entity)(gc_scene *scene, gc_entity *entity);
+    gc_entity *(*get_entity)(gc_scene *scene, int id);
+    gc_list *(*get_entity_by_cmp)(gc_scene *scene, const char *cmp_name);
 };
 
 gc_scene *scene_create(const char **textures);
diff --git a/include/tupple.h b/include/tupple.h
new file mode 100644
index 0000000..47c83e0
--- /dev/null
+++ b/include/tupple.h
@@ -0,0 +1,22 @@
+/*
+** EPITECH PROJECT, 2019
+** MUL_my_runner_2019
+** File description:
+** tupple
+*/
+
+typedef struct gc_tupple gc_tupple;
+
+#pragma once
+
+#include "list.h"
+#include "entity.h"
+
+struct gc_tupple
+{
+    char *name;
+    gc_list *entities;
+    gc_tupple *next;
+};
+
+gc_tupple *tupple_add(gc_tupple *list, const char *name, gc_entity *entity);
\ No newline at end of file
diff --git a/src/deserializer/prefab.c b/src/deserializer/prefab.c
index cdda201..0d8431e 100644
--- a/src/deserializer/prefab.c
+++ b/src/deserializer/prefab.c
@@ -14,15 +14,22 @@
 #include <unistd.h>
 #include <fcntl.h>
 
-gc_entity *prefab_load(gc_engine *engine, const char *path)
+int prefab_load(gc_engine *engine, const char *path)
 {
-    gc_entity *entity = NULL;
-    node *n = xml_parse(path);
+    node *n;
+    gc_entity *entity;
 
+    if (!engine || !engine->scene)
+        return (-1);
+    n = xml_parse(path);
     if (!n)
-        return (NULL);
-    for (node *ent_n = n->child; ent_n; ent_n = ent_n->next)
-        entity = entity_add(entity, deserialize_entity(engine, ent_n));
+        return (-1);
+    for (node *ent_n = n->child; ent_n; ent_n = ent_n->next) {
+        entity = deserialize_entity(engine, ent_n);
+        if (!entity)
+            return (-1);
+        engine->scene->add_entity(engine->scene, entity);
+    }
     xml_destroy(n);
-    return (entity);
+    return (0);
 }
diff --git a/src/engine/engine.c b/src/engine/engine.c
index cb39058..9b7550f 100644
--- a/src/engine/engine.c
+++ b/src/engine/engine.c
@@ -12,22 +12,27 @@
 #include <SFML/Graphics.h>
 #include <SFML/System.h>
 
-void update_entity(gc_engine *engine, gc_entity *entity, float dtime)
+void update_system(gc_engine *engine, gc_system *sys, float dtime)
 {
-    for (gc_list *sys = engine->systems; sys; sys = sys->next) {
-        if (((gc_system *)sys->data)->check_dependencies(sys->data, entity))
-            ((gc_system *)sys->data)->update_entity(engine, entity, dtime);
+    gc_scene *scene = engine->scene;
+    gc_list *entities;
+    
+    if (!scene)
+        return;
+    entities = scene->get_entity_by_cmp(scene, sys->component_name);
+    for (gc_list *entity = entities; entity; entity = entity->next) {
+        if (sys->check_dependencies(sys, entity->data))
+            sys->update_entity(engine, entity->data, dtime);
     }
 }
 
 int game_loop(gc_engine *engine)
 {
-    gc_entity *entities = engine->scene->entities;
     float dtime = sfTime_asSeconds(sfClock_restart(engine->clock));
 
     handle_events(engine);
-    for (gc_entity *entity = entities; entity; entity = entity->next)
-        update_entity(engine, entity, dtime);
+    for (gc_list *sys = engine->systems; sys; sys = sys->next)
+        update_system(engine, sys->data, dtime);
     engine->draw(engine);
     return (0);
 }
diff --git a/src/engine/engine_component_builder.c b/src/engine/engine_component_builder.c
index 1e0abdd..c19c9f6 100644
--- a/src/engine/engine_component_builder.c
+++ b/src/engine/engine_component_builder.c
@@ -15,23 +15,7 @@
 
 void engine_add_component(gc_engine *engine, const void *component)
 {
-    gc_list *components = engine->components;
-
-    if (!components) {
-        engine->components = malloc(sizeof(gc_list));
-        if (!engine->components)
-            return;
-        engine->components->data = (void *)component;
-        engine->components->next = NULL;
-    } else {
-        while (components->next)
-            components = components->next;
-        components->next = malloc(sizeof(gc_list));
-        if (!components->next)
-            return;
-        components->next->data = (void *)component;
-        components->next->next = NULL;
-    }
+    engine->components = list_add(engine->components, (void *)component);
 }
 
 void engine_add_buildin_components(gc_engine *engine)
diff --git a/src/engine/engine_system_builder.c b/src/engine/engine_system_builder.c
index 19fd389..d68c189 100644
--- a/src/engine/engine_system_builder.c
+++ b/src/engine/engine_system_builder.c
@@ -13,23 +13,7 @@
 
 void engine_add_system(gc_engine *engine, const gc_system *system)
 {
-    gc_list *systems = engine->systems;
-
-    if (!systems) {
-        engine->systems = malloc(sizeof(gc_list));
-        if (!engine->systems)
-            return;
-        engine->systems->data = (void *)system;
-        engine->systems->next = NULL;
-    } else {
-        while (systems->next)
-            systems = systems->next;
-        systems->next = malloc(sizeof(gc_list));
-        if (!systems->next)
-            return;
-        systems->next->data = (void *)system;
-        systems->next->next = NULL;
-    }
+    engine->systems = list_add(engine->systems, (void *)system);
 }
 
 void engine_add_buildin_systems(gc_engine *engine)
diff --git a/src/entity/entity.c b/src/entity/entity.c
index e2b8205..0aff1c0 100644
--- a/src/entity/entity.c
+++ b/src/entity/entity.c
@@ -10,6 +10,15 @@
 #include <stdlib.h>
 #include <unistd.h>
 
+gc_entity *entity_get(gc_scene *scene, int id)
+{
+    for (gc_list *ent = scene->entities; ent; ent = ent->next) {
+        if (((gc_entity *)ent->data)->id == id)
+            return (ent->data);
+    }
+    return (NULL);
+}
+
 void *entity_get_component(const gc_entity *entity, const char *name)
 {
     for (gc_component *cmp = entity->components; cmp; cmp = cmp->next) {
@@ -58,7 +67,5 @@ const gc_entity entity_prefab = {
     get_component: &entity_get_component,
     has_component: &entity_has_component,
     serialize: &entity_serialize,
-    destroy: &destroy,
-    next: NULL,
-    prev: NULL
+    destroy: &destroy
 };
\ No newline at end of file
diff --git a/src/entity/entity_factory.c b/src/entity/entity_factory.c
index 4196d39..b5e4335 100644
--- a/src/entity/entity_factory.c
+++ b/src/entity/entity_factory.c
@@ -35,19 +35,20 @@ gc_entity *entity_create_with_id(int id)
     return (entity);
 }
 
-gc_entity *entity_add(gc_entity *list, gc_entity *entity)
+int entity_add(gc_scene *scene, gc_entity *e)
 {
-    gc_entity *list_const = list;
+    char *name;
 
-    if (!list) {
-        return (entity);
-    } else {
-        while (list->next)
-            list = list->next;
-        list->next = entity;
-        entity->prev = list;
-        return (list_const);
+    scene->entities = list_add(scene->entities, e);
+    if (!scene->entities)
+        return (-1);
+    for (gc_component *cmp = e->components; cmp; cmp =  cmp->next) {
+        name = cmp->name;
+        scene->entities_by_cmp = tupple_add(scene->entities_by_cmp, name, e);
+        if (!scene->entities_by_cmp)
+            return (-1);
     }
+    return (0);
 }
 
 gc_entity *entity_add_component(gc_entity *entity, void *component)
diff --git a/src/scene/scene.c b/src/scene/scene.c
index 4dddbd7..54e01aa 100644
--- a/src/scene/scene.c
+++ b/src/scene/scene.c
@@ -11,12 +11,13 @@
 #include "utility.h"
 #include <stdlib.h>
 
-int scene_add_entity(gc_scene *scene, gc_entity *entity)
+gc_list *get_entity_by_cmp(gc_scene *scene, const char *cmp_name)
 {
-    if (!scene || !entity)
-        return (-1);
-    scene->entities = entity_add(scene->entities, entity);
-    return (0);
+    for (gc_tupple *tup = scene->entities_by_cmp; tup; tup = tup->next) {
+        if (!my_strcmp(tup->name, cmp_name))
+            return (tup->entities);
+    }
+    return (NULL);
 }
 
 int scene_load_textures(gc_scene *scene, const char **textures)
@@ -37,11 +38,11 @@ int scene_load_textures(gc_scene *scene, const char **textures)
 
 void scene_destroy(gc_scene *scene)
 {
-    gc_entity *next = NULL;
+    gc_list *next = NULL;
 
-    for (gc_entity *entity = scene->entities; entity; entity = next) {
+    for (gc_list *entity = scene->entities; entity; entity = next) {
         next = entity->next;
-        entity->destroy(entity);
+        ((gc_entity *)entity->data)->destroy(entity->data);
     }
     for (int i = 0; scene->textures[i]; i++) {
         scene->textures[i]->destroy(scene->textures[i]);
@@ -59,7 +60,10 @@ gc_scene *scene_create(const char **textures)
     if (textures && scene_load_textures(scene, textures) < 0)
         return (NULL);
     scene->entities = NULL;
-    scene->add_entity = &scene_add_entity;
+    scene->entities_by_cmp = NULL;
+    scene->add_entity = &entity_add;
+    scene->get_entity = &entity_get;
+    scene->get_entity_by_cmp = &get_entity_by_cmp;
     scene->destroy = &scene_destroy;
     return (scene);
 }
\ No newline at end of file
diff --git a/src/utility/list.c b/src/utility/list.c
new file mode 100644
index 0000000..da5154a
--- /dev/null
+++ b/src/utility/list.c
@@ -0,0 +1,29 @@
+/*
+** EPITECH PROJECT, 2019
+** MUL_my_runner_2019
+** File description:
+** list
+*/
+
+#include "list.h"
+#include <stdlib.h>
+
+gc_list *list_add(gc_list *list, void *obj)
+{
+    gc_list *listconst = list;
+
+    if (!list) {
+        list = malloc(sizeof(gc_list));
+        listconst = list;
+    } else {
+        while (list->next)
+            list = list->next;
+        list->next = malloc(sizeof(gc_list));
+        list = list->next;
+    }
+    if (!list)
+        return (NULL);
+    list->data = obj;
+    list->next = NULL;
+    return (listconst);
+}
\ No newline at end of file
diff --git a/src/utility/tupple.c b/src/utility/tupple.c
new file mode 100644
index 0000000..5e6f67f
--- /dev/null
+++ b/src/utility/tupple.c
@@ -0,0 +1,44 @@
+/*
+** EPITECH PROJECT, 2019
+** MUL_my_runner_2019
+** File description:
+** tupple
+*/
+
+#include "tupple.h"
+#include "entity.h"
+#include "utility.h"
+#include <stdlib.h>
+
+static int tupple_add_existing(gc_tupple *l, const char *name, gc_entity *ent)
+{
+    while (l && my_strcmp(l->name, name))
+        l = l->next;
+    if (!l)
+        return (-1);
+    l->entities = list_add(l->entities, ent);
+    return (0);
+}
+
+gc_tupple *tupple_add(gc_tupple *list, const char *name, gc_entity *entity)
+{
+    gc_tupple *listconst = list;
+
+    if (!list) {
+        list = malloc(sizeof(gc_tupple));
+        listconst = list;
+    } else {
+        if (!tupple_add_existing(list, name, entity))
+            return (listconst);
+        while (list->next)
+            list = list->next;
+        list->next = malloc(sizeof(gc_tupple));
+        list = list->next;
+    }
+    if (!list)
+        return (NULL);
+    list->name = my_strdup(name);
+    list->entities = list_add(NULL, entity);
+    list->next = NULL;
+    return (listconst);
+}
\ No newline at end of file