diff --git a/server/gameserver/collider.cc b/server/gameserver/collider.cc
index 0d17fb2..b7ebb3a 100644
--- a/server/gameserver/collider.cc
+++ b/server/gameserver/collider.cc
@@ -1,9 +1,77 @@
 #include "precompile.h"
 
+#include <algorithm>
+
 #include "entity.h"
 #include "collider.h"
 
+static bool IntersectAabbCircle(AabbCollider* a, CircleCollider* b)
+{
+    if (b->pos.x >= a->_min.x && b->pos.x <= a->_max.x &&
+        b->pos.y >= a->_min.y && b->pos.y <= a->_max.y) {
+        return true;
+    }
+    Vector2D nearest_point(a8::Clamp(b->pos.x, a->_min.x, a->_max.y),
+                           a8::Clamp(b->pos.y, a->_min.y, a->_max.y));
+    Vector2D i = b->pos - nearest_point;
+    float n = a8::LengthSqr(i);
+    return n < b->rad*b->rad;
+}
+
+static bool IntersectAabbAabb(AabbCollider* a, AabbCollider* b)
+{
+    Vector2D a_v = (a->_max - a->_min) * 0.5f;
+    Vector2D a_center = a->_min + a_v;
+    Vector2D b_v = (b->_max - b->_min) * 0.5f;
+    Vector2D b_center = b->_min + b_v;
+    Vector2D z = b_center - a_center;
+    float u = a_v.x + b_v.x - std::abs(z.x);
+    return u > 0;
+}
+
+static bool IntersectCircleCircle(CircleCollider* a, CircleCollider* b)
+{
+    float t = a->rad + b->rad;
+    Vector2D d = b->pos - a->pos;
+    float n = a8::LengthSqr(d);
+    return n < t*t;
+}
+
 bool ColliderComponent::Intersect(ColliderComponent* b)
 {
+    switch (type) {
+    case CT_Aabb:
+        {
+            switch (b->type) {
+            case CT_Aabb:
+                {
+                    return IntersectAabbAabb((AabbCollider*)this, (AabbCollider*)b);
+                }
+                break;
+            case CT_Circle:
+                {
+                    return IntersectAabbCircle((AabbCollider*)this, (CircleCollider*)b);
+                }
+                break;
+            }
+        };
+        break;
+    case CT_Circle:
+        {
+            switch (b->type) {
+            case CT_Aabb:
+                {
+                    return IntersectAabbCircle((AabbCollider*)b, (CircleCollider*)this);
+                }
+                break;
+            case CT_Circle:
+                {
+                    return IntersectCircleCircle((CircleCollider*)this, (CircleCollider*)b);
+                }
+                break;
+            }
+        }
+        break;
+    }
     return false;
 }
diff --git a/server/gameserver/room.cc b/server/gameserver/room.cc
index f6cd733..eef1fd8 100644
--- a/server/gameserver/room.cc
+++ b/server/gameserver/room.cc
@@ -40,12 +40,15 @@ Player* Room::GetPlayerByAccountId(const std::string& accountid)
 }
 
 Player* Room::GetPlayerByUniId(unsigned short uniid)
+{
+    Entity* entity = GetEntityByUniId(uniid);
+    return entity->entity_type == ET_Player && entity->entity_subtype == EST_Player ? (Player*)entity : nullptr;
+}
+
+Entity* Room::GetEntityByUniId(unsigned short uniid)
 {
     auto itr = uniid_hash_.find(uniid);
-    return itr != uniid_hash_.end() &&
-        itr->second->entity_type == ET_Player &&
-        itr->second->entity_subtype == EST_Player ?
-        (Player*)itr->second : nullptr;
+    return itr != uniid_hash_.end() ? itr->second : nullptr;
 }
 
 int Room::AliveCount()
@@ -65,7 +68,8 @@ void Room::AddPlayer(Player* hum)
 
 unsigned short Room::AllocUniid()
 {
-    return ++current_uniid;
+    while (GetEntityByUniId(++current_uniid)) {}
+    return current_uniid;
 }
 
 void Room::ShuaAndroid()
@@ -90,6 +94,9 @@ void Room::ShuaAndroid()
 
 bool Room::RandomPos(Human* hum, float distance, Vector2D& out_pos)
 {
+    for (auto& pair : uniid_hash_) {
+
+    }
     return false;
 }
 
diff --git a/server/gameserver/room.h b/server/gameserver/room.h
index f3b70d0..66e6bcb 100644
--- a/server/gameserver/room.h
+++ b/server/gameserver/room.h
@@ -36,12 +36,13 @@ public:
     int AliveCount();
     Player* GetPlayerByAccountId(const std::string& accountid);
     Player* GetPlayerByUniId(unsigned short uniid);
+    Entity* GetEntityByUniId(unsigned short uniid);
     void AddPlayer(Player* hum);
+    void AddBullet(Bullet* bullet);
     unsigned short AllocUniid();
     void ShuaAndroid();
     bool RandomPos(Human* hum, float distance, Vector2D& out_pos);
     Human* SearchEnemy(Human* hum);
-    void AddBullet(Bullet* bullet);
 
  private:
     unsigned short current_uniid = 0;
diff --git a/third_party/a8engine b/third_party/a8engine
index e2f4d2c..1eaf2da 160000
--- a/third_party/a8engine
+++ b/third_party/a8engine
@@ -1 +1 @@
-Subproject commit e2f4d2c9a4bb653ad6b37413d3dc3d9ca217a8de
+Subproject commit 1eaf2da087ab028b1b859551605bdf8a32f683e5