diff --git a/src/ChunkManager.cpp b/src/ChunkManager.cpp
index a9fcec1..3c7e335 100644
--- a/src/ChunkManager.cpp
+++ b/src/ChunkManager.cpp
@@ -3,12 +3,12 @@
 #include "NPCManager.hpp"
 #include "settings.hpp"
 
-std::map<std::pair<int, int>, Chunk*> ChunkManager::chunks;
+std::map<std::tuple<int, int, int>, Chunk*> ChunkManager::chunks;
 
 void ChunkManager::init() {} // stubbed
 
-void ChunkManager::addNPC(int posX, int posY, int32_t id) {
-    std::pair<int, int> pos = grabChunk(posX, posY);
+void ChunkManager::addNPC(int posX, int posY, int instanceID, int32_t id) {
+    std::tuple<int, int, int> pos = grabChunk(posX, posY, instanceID);
 
     // make chunk if it doesn't exist!
     if (chunks.find(pos) == chunks.end()) {
@@ -22,8 +22,8 @@ void ChunkManager::addNPC(int posX, int posY, int32_t id) {
     chunk->NPCs.insert(id);
 }
 
-void ChunkManager::addPlayer(int posX, int posY, CNSocket* sock) {
-    std::pair<int, int> pos = grabChunk(posX, posY);
+void ChunkManager::addPlayer(int posX, int posY, int instanceID, CNSocket* sock) {
+    std::tuple<int, int, int> pos = grabChunk(posX, posY, instanceID);
 
     // make chunk if it doesn't exist!
     if (chunks.find(pos) == chunks.end()) {
@@ -37,7 +37,7 @@ void ChunkManager::addPlayer(int posX, int posY, CNSocket* sock) {
     chunk->players.insert(sock);
 }
 
-void ChunkManager::removePlayer(std::pair<int, int> chunkPos, CNSocket* sock) {
+void ChunkManager::removePlayer(std::tuple<int, int, int> chunkPos, CNSocket* sock) {
     if (!checkChunk(chunkPos))
         return; // do nothing if chunk doesn't even exist
     
@@ -48,7 +48,7 @@ void ChunkManager::removePlayer(std::pair<int, int> chunkPos, CNSocket* sock) {
     // TODO: if players and NPCs are empty, free chunk and remove it from surrounding views
 }
 
-void ChunkManager::removeNPC(std::pair<int, int> chunkPos, int32_t id) {
+void ChunkManager::removeNPC(std::tuple<int, int, int> chunkPos, int32_t id) {
     if (!checkChunk(chunkPos))
         return; // do nothing if chunk doesn't even exist
 
@@ -59,22 +59,25 @@ void ChunkManager::removeNPC(std::pair<int, int> chunkPos, int32_t id) {
     // TODO: if players and NPCs are empty, free chunk and remove it from surrounding views
 }
 
-bool ChunkManager::checkChunk(std::pair<int, int> chunk) {
+bool ChunkManager::checkChunk(std::tuple<int, int, int> chunk) {
     return chunks.find(chunk) != chunks.end();
 }
 
-std::pair<int, int> ChunkManager::grabChunk(int posX, int posY) {
-    return std::make_pair<int, int>(posX / (settings::CHUNKSIZE / 3), posY / (settings::CHUNKSIZE / 3));
+std::tuple<int, int, int> ChunkManager::grabChunk(int posX, int posY, int instanceID) {
+    return std::make_tuple(posX / (settings::CHUNKSIZE / 3), posY / (settings::CHUNKSIZE / 3), instanceID);
 }
 
-std::vector<Chunk*> ChunkManager::grabChunks(std::pair<int, int> chunk) {
+std::vector<Chunk*> ChunkManager::grabChunks(std::tuple<int, int, int> chunk) {
     std::vector<Chunk*> chnks;
     chnks.reserve(9);
 
+    int x, y, inst;
+    std::tie(x, y, inst) = chunk;
+
     // grabs surrounding chunks if they exist
     for (int i = -1; i < 2; i++) {
         for (int z = -1; z < 2; z++) {
-            std::pair<int, int> pos(chunk.first+i, chunk.second+z);
+            std::tuple<int, int, int> pos = std::make_tuple(x+i, y+z, inst);
             
             // if chunk exists, add it to the vector
             if (checkChunk(pos))
@@ -108,8 +111,8 @@ std::vector<Chunk*> ChunkManager::getDeltaChunks(std::vector<Chunk*> from, std::
     return delta;
 }
 
-bool ChunkManager::inPopulatedChunks(int posX, int posY) {
-    auto chunk = ChunkManager::grabChunk(posX, posY);
+bool ChunkManager::inPopulatedChunks(int posX, int posY, int instanceID) {
+    auto chunk = ChunkManager::grabChunk(posX, posY, instanceID);
     auto nearbyChunks = ChunkManager::grabChunks(chunk);
 
     for (Chunk *c: nearbyChunks) {
diff --git a/src/ChunkManager.hpp b/src/ChunkManager.hpp
index 97d061a..cdcdb5c 100644
--- a/src/ChunkManager.hpp
+++ b/src/ChunkManager.hpp
@@ -6,6 +6,7 @@
 #include <vector>
 #include <set>
 #include <map>
+#include <tuple>
 
 class Chunk {
 public:
@@ -13,19 +14,25 @@ public:
     std::set<int32_t> NPCs;
 };
 
+enum {
+    INSTANCE_OVERWORLD, // default instance every player starts in
+    INSTANCE_IZ, // all infected zones share an instance
+    INSTANCE_UNIQUE // fusion lairs are generated as requested (+ uid)
+};
+
 namespace ChunkManager {
     void init();
     void cleanup();
 
-    extern std::map<std::pair<int, int>, Chunk*> chunks;
+    extern std::map<std::tuple<int, int, int>, Chunk*> chunks;
 
-    void addNPC(int posX, int posY, int32_t id);
-    void addPlayer(int posX, int posY, CNSocket* sock);
-    void removePlayer(std::pair<int, int> chunkPos, CNSocket* sock);
-    void removeNPC(std::pair<int, int> chunkPos, int32_t id);
-    bool checkChunk(std::pair<int, int> chunk);
-    std::pair<int, int> grabChunk(int posX, int posY);
-    std::vector<Chunk*> grabChunks(std::pair<int, int> chunkPos);
+    void addNPC(int posX, int posY, int instanceID, int32_t id);
+    void addPlayer(int posX, int posY, int instanceID, CNSocket* sock);
+    void removePlayer(std::tuple<int, int, int> chunkPos, CNSocket* sock);
+    void removeNPC(std::tuple<int, int, int> chunkPos, int32_t id);
+    bool checkChunk(std::tuple<int, int, int> chunk);
+    std::tuple<int, int, int> grabChunk(int posX, int posY, int instanceID);
+    std::vector<Chunk*> grabChunks(std::tuple<int, int, int> chunkPos);
     std::vector<Chunk*> getDeltaChunks(std::vector<Chunk*> from, std::vector<Chunk*> to);
-    bool inPopulatedChunks(int posX, int posY);
+    bool inPopulatedChunks(int posX, int posY, int instanceID);
 }
diff --git a/src/MobManager.cpp b/src/MobManager.cpp
index dd33502..402da94 100644
--- a/src/MobManager.cpp
+++ b/src/MobManager.cpp
@@ -457,7 +457,7 @@ void MobManager::step(CNServer *serv, time_t currTime) {
         int y = pair.second->appearanceData.iY;
 
         // skip chunks without players
-        if (!ChunkManager::inPopulatedChunks(x, y))
+        if (!ChunkManager::inPopulatedChunks(x, y, pair.second->instanceID))
             continue;
 
         // skip mob movement and combat if disabled
diff --git a/src/MobManager.hpp b/src/MobManager.hpp
index 879d273..234a090 100644
--- a/src/MobManager.hpp
+++ b/src/MobManager.hpp
@@ -42,8 +42,8 @@ struct Mob : public BaseNPC {
     // temporary; until we're sure what's what
     nlohmann::json data;
 
-    Mob(int x, int y, int z, int type, int hp, int angle, nlohmann::json d, int32_t id)
-        : BaseNPC(x, y, z, type, id), maxHealth(hp) {
+    Mob(int x, int y, int z, int iID, int type, int hp, int angle, nlohmann::json d, int32_t id)
+        : BaseNPC(x, y, z, iID, type, id), maxHealth(hp) {
         state = MobState::ROAMING;
 
         data = d;
@@ -68,8 +68,8 @@ struct Mob : public BaseNPC {
     }
 
     // constructor for /summon
-    Mob(int x, int y, int z, int type, nlohmann::json d, int32_t id)
-        : Mob(x, y, z, type, 0, 0, d, id) {
+    Mob(int x, int y, int z, int iID, int type, nlohmann::json d, int32_t id)
+        : Mob(x, y, z, iID, type, 0, 0, d, id) {
         summoned = true; // will be despawned and deallocated when killed
         appearanceData.iHP = maxHealth = d["m_iHP"];
     }
diff --git a/src/NPC.hpp b/src/NPC.hpp
index 3dffe27..c48b5c9 100644
--- a/src/NPC.hpp
+++ b/src/NPC.hpp
@@ -7,11 +7,12 @@ class BaseNPC {
 public:
     sNPCAppearanceData appearanceData;
     NPCClass npcClass;
-    std::pair<int, int> chunkPos;
+    int instanceID;
+    std::tuple<int, int, int> chunkPos;
     std::vector<Chunk*> currentChunks;
 
     BaseNPC() {};
-    BaseNPC(int x, int y, int z, int type, int id) {
+    BaseNPC(int x, int y, int z, int iID, int type, int id) {
         appearanceData.iX = x;
         appearanceData.iY = y;
         appearanceData.iZ = z;
@@ -22,9 +23,11 @@ public:
         appearanceData.iBarkerType = 0;
         appearanceData.iNPC_ID = id;
 
-        chunkPos = std::pair<int, int>(0, 0);
+        instanceID = iID;
+
+        chunkPos = std::make_tuple(0, 0, instanceID);
     };
-    BaseNPC(int x, int y, int z, int type, int id, NPCClass classType) : BaseNPC(x, y, z, type, id) {
+    BaseNPC(int x, int y, int z, int iID, int type, int id, NPCClass classType) : BaseNPC(x, y, z, iID, type, id) {
         npcClass = classType;
     }
 };
diff --git a/src/NPCManager.cpp b/src/NPCManager.cpp
index b78ea49..4ac22c7 100644
--- a/src/NPCManager.cpp
+++ b/src/NPCManager.cpp
@@ -140,7 +140,7 @@ void NPCManager::updateNPCPosition(int32_t id, int X, int Y, int Z) {
     npc->appearanceData.iX = X;
     npc->appearanceData.iY = Y;
     npc->appearanceData.iZ = Z;
-    std::pair<int, int> newPos = ChunkManager::grabChunk(X, Y);
+    std::tuple<int, int, int> newPos = ChunkManager::grabChunk(X, Y, npc->instanceID);
 
     // nothing to be done (but we should also update currentChunks to add/remove stale chunks)
     if (newPos == npc->chunkPos) {
@@ -158,7 +158,7 @@ void NPCManager::updateNPCPosition(int32_t id, int X, int Y, int Z) {
 
     // update chunks
     ChunkManager::removeNPC(npc->chunkPos, id);
-    ChunkManager::addNPC(X, Y, id);
+    ChunkManager::addNPC(X, Y, npc->instanceID, id);
 
     npc->chunkPos = newPos;
     npc->currentChunks = allChunks;
@@ -544,10 +544,10 @@ void NPCManager::npcSummonHandler(CNSocket* sock, CNPacketData* data) {
     resp.NPCAppearanceData.iZ = plr->z;
 
     if (team == 2) {
-        NPCs[resp.NPCAppearanceData.iNPC_ID] = new Mob(plr->x, plr->y, plr->z, req->iNPCType, NPCData[req->iNPCType], resp.NPCAppearanceData.iNPC_ID);
+        NPCs[resp.NPCAppearanceData.iNPC_ID] = new Mob(plr->x, plr->y, plr->z, plr->instanceID, req->iNPCType, NPCData[req->iNPCType], resp.NPCAppearanceData.iNPC_ID);
         MobManager::Mobs[resp.NPCAppearanceData.iNPC_ID] = (Mob*)NPCs[resp.NPCAppearanceData.iNPC_ID];
     } else
-        NPCs[resp.NPCAppearanceData.iNPC_ID] = new BaseNPC(plr->x, plr->y, plr->z, req->iNPCType, resp.NPCAppearanceData.iNPC_ID);
+        NPCs[resp.NPCAppearanceData.iNPC_ID] = new BaseNPC(plr->x, plr->y, plr->z, plr->instanceID, req->iNPCType, resp.NPCAppearanceData.iNPC_ID);
 
     updateNPCPosition(resp.NPCAppearanceData.iNPC_ID, plr->x, plr->y, plr->z);
 }
@@ -585,7 +585,7 @@ void NPCManager::handleWarp(CNSocket* sock, int32_t warpId) {
     // force player & NPC reload
     PlayerManager::removePlayerFromChunks(plrv.currentChunks, sock);
     plrv.currentChunks.clear();
-    plrv.chunkPos = std::make_pair<int, int>(0, 0);
+    plrv.chunkPos = std::make_tuple(0, 0, plrv.plr->instanceID);
 
     sock->sendPacket((void*)&resp, P_FE2CL_REP_PC_WARP_USE_NPC_SUCC, sizeof(sP_FE2CL_REP_PC_WARP_USE_NPC_SUCC));
 }
diff --git a/src/Player.hpp b/src/Player.hpp
index 26804df..51b21c8 100644
--- a/src/Player.hpp
+++ b/src/Player.hpp
@@ -37,7 +37,7 @@ struct Player {
     int32_t iConditionBitFlag;
     int8_t iSpecialState;
 
-    int x, y, z, angle;
+    int x, y, z, angle, instanceID;
     sItemBase Equip[AEQUIP_COUNT];
     sItemBase Inven[AINVEN_COUNT];
     sItemBase Bank[ABANK_COUNT];
diff --git a/src/PlayerManager.cpp b/src/PlayerManager.cpp
index 6fac1a1..6baf8bf 100644
--- a/src/PlayerManager.cpp
+++ b/src/PlayerManager.cpp
@@ -47,7 +47,7 @@ void PlayerManager::addPlayer(CNSocket* key, Player plr) {
     memcpy(p, &plr, sizeof(Player));
 
     players[key] = PlayerView();
-    players[key].chunkPos = std::make_pair<int, int>(0, 0);
+    players[key].chunkPos = std::make_tuple(0, 0, p->instanceID);
     players[key].currentChunks = std::vector<Chunk*>();
     players[key].plr = p;
     players[key].lastHeartbeat = 0;
@@ -191,7 +191,7 @@ void PlayerManager::updatePlayerPosition(CNSocket* sock, int X, int Y, int Z) {
 
 void PlayerManager::updatePlayerChunk(CNSocket* sock, int X, int Y) {
     PlayerView& view = players[sock];
-    std::pair<int, int> newPos = ChunkManager::grabChunk(X, Y);
+    std::tuple<int, int, int> newPos = ChunkManager::grabChunk(X, Y, view.plr->instanceID);
 
     // nothing to be done
     if (newPos == view.chunkPos)
@@ -206,7 +206,7 @@ void PlayerManager::updatePlayerChunk(CNSocket* sock, int X, int Y) {
     // now, add all the new npcs & players!
     addPlayerToChunks(ChunkManager::getDeltaChunks(allChunks, view.currentChunks), sock);
 
-    ChunkManager::addPlayer(X, Y, sock); // takes care of adding the player to the chunk if it exists or not
+    ChunkManager::addPlayer(X, Y, view.plr->instanceID, sock); // takes care of adding the player to the chunk if it exists or not
     view.chunkPos = newPos;
     view.currentChunks = allChunks;
 }
@@ -309,6 +309,7 @@ void PlayerManager::enterPlayer(CNSocket* sock, CNPacketData* data) {
     response.PCLoadData2CL.iFirstUseFlag2 = UINT64_MAX;
 
     plr.SerialKey = enter->iEnterSerialKey;
+    plr.instanceID = INSTANCE_OVERWORLD; // TODO: load this from the database (as long as it's not a unique instance)
 
     motd.iType = 1;
     U8toU16(settings::MOTDSTRING, (char16_t*)motd.szSystemMsg);
@@ -647,7 +648,7 @@ void PlayerManager::gotoPlayer(CNSocket* sock, CNPacketData* data) {
     // force player & NPC reload
     PlayerManager::removePlayerFromChunks(plrv.currentChunks, sock);
     plrv.currentChunks.clear();
-    plrv.chunkPos = std::make_pair<int, int>(0, 0);
+    plrv.chunkPos = std::make_tuple(0, 0, plrv.plr->instanceID);
 
     sock->sendPacket((void*)&response, P_FE2CL_REP_PC_GOTO_SUCC, sizeof(sP_FE2CL_REP_PC_GOTO_SUCC));
 }
diff --git a/src/PlayerManager.hpp b/src/PlayerManager.hpp
index 44a5b24..f4fafb4 100644
--- a/src/PlayerManager.hpp
+++ b/src/PlayerManager.hpp
@@ -13,7 +13,7 @@
 struct WarpLocation;
 
 struct PlayerView {
-    std::pair<int, int> chunkPos;
+    std::tuple<int, int, int> chunkPos;
     std::vector<Chunk*> currentChunks;
     Player *plr;
     time_t lastHeartbeat;
diff --git a/src/TableData.cpp b/src/TableData.cpp
index b15b978..94c6bbc 100644
--- a/src/TableData.cpp
+++ b/src/TableData.cpp
@@ -25,7 +25,7 @@ void TableData::init() {
 
         for (nlohmann::json::iterator _npc = npcData.begin(); _npc != npcData.end(); _npc++) {
             auto npc = _npc.value();
-            BaseNPC *tmp = new BaseNPC(npc["x"], npc["y"], npc["z"], npc["id"], nextId);
+            BaseNPC *tmp = new BaseNPC(npc["x"], npc["y"], npc["z"], INSTANCE_OVERWORLD, npc["id"], nextId);
 
             NPCManager::NPCs[nextId] = tmp;
             NPCManager::updateNPCPosition(nextId, npc["x"], npc["y"], npc["z"]);
@@ -179,7 +179,7 @@ void TableData::init() {
         for (nlohmann::json::iterator _npc = npcData.begin(); _npc != npcData.end(); _npc++) {
             auto npc = _npc.value();
             auto td = NPCManager::NPCData[(int)npc["iNPCType"]];
-            Mob *tmp = new Mob(npc["iX"], npc["iY"], npc["iZ"], npc["iNPCType"], npc["iHP"], npc["iAngle"], td, nextId);
+            Mob *tmp = new Mob(npc["iX"], npc["iY"], npc["iZ"], INSTANCE_OVERWORLD, npc["iNPCType"], npc["iHP"], npc["iAngle"], td, nextId);
 
             NPCManager::NPCs[nextId] = tmp;
             MobManager::Mobs[nextId] = (Mob*)NPCManager::NPCs[nextId];
diff --git a/src/TransportManager.cpp b/src/TransportManager.cpp
index 91c70f8..ab3fc9e 100644
--- a/src/TransportManager.cpp
+++ b/src/TransportManager.cpp
@@ -149,7 +149,7 @@ void TransportManager::transportWarpHandler(CNSocket* sock, CNPacketData* data)
          */
         PlayerManager::removePlayerFromChunks(plrv.currentChunks, sock);
         plrv.currentChunks.clear();
-        plrv.chunkPos = std::make_pair<int, int>(0, 0);
+        plrv.chunkPos = std::make_tuple(0, 0, plrv.plr->instanceID);
         break;
     case 2: // Monkey Skyway
         if (SkywayPaths.find(route.mssRouteNum) != SkywayPaths.end()) { // check if route exists
@@ -268,7 +268,7 @@ void TransportManager::stepNPCPathing() {
         NPCManager::updateNPCPosition(npc->appearanceData.iNPC_ID, point.x, point.y, point.z);
 
         // get chunks in view
-        auto chunk = ChunkManager::grabChunk(npc->appearanceData.iX, npc->appearanceData.iY);
+        auto chunk = ChunkManager::grabChunk(npc->appearanceData.iX, npc->appearanceData.iY, npc->instanceID);
         auto chunks = ChunkManager::grabChunks(chunk);
 
         switch (npc->npcClass) {