diff --git a/main.go b/cmd/main.go
similarity index 100%
rename from main.go
rename to cmd/main.go
diff --git a/main_test.go b/cmd/main_test.go
similarity index 100%
rename from main_test.go
rename to cmd/main_test.go
diff --git a/overlord.go b/overlord.go
deleted file mode 100644
index 4a9795f8..00000000
--- a/overlord.go
+++ /dev/null
@@ -1,123 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"log"
-	"math/rand"
-	"net/http"
-	"strconv"
-
-	"github.com/giongto35/cloud-game/webrtc"
-)
-
-var roomToServer = map[string]string{}
-
-// servers are the map serverID to server Client
-var servers = map[string]*Client{}
-
-// If it's overlord, handle overlord connection (from host to overlord)
-func wso(w http.ResponseWriter, r *http.Request) {
-	fmt.Println("Connected")
-	c, err := upgrader.Upgrade(w, r, nil)
-	if err != nil {
-		log.Print("[!] WS upgrade:", err)
-		return
-	}
-	defer c.Close()
-
-	// register new server
-	serverID := strconv.Itoa(rand.Int())
-	log.Println("A new server connected ", serverID)
-
-	client := NewClient(c)
-	servers[serverID] = client
-
-	wssession := &Session{
-		client:         client,
-		peerconnection: webrtc.NewWebRTC(),
-		// The server session is maintaining
-	}
-
-	client.send(
-		WSPacket{
-			ID:   "serverID",
-			Data: serverID,
-		},
-		nil,
-	)
-
-	client.receive("registerRoom", func(resp WSPacket) WSPacket {
-		log.Println("Received registerRoom ", resp.Data, serverID)
-		roomToServer[resp.Data] = serverID
-		return WSPacket{
-			ID: "registerRoom",
-		}
-	})
-
-	client.receive("getRoom", func(resp WSPacket) WSPacket {
-		log.Println("Received a getroom request")
-		return WSPacket{
-			ID:   "getRoom",
-			Data: roomToServer[resp.Data],
-		}
-	})
-
-	client.receive("initwebrtc", func(resp WSPacket) WSPacket {
-		log.Println("Received a relay sdp request from a host")
-		// TODO: Abstract
-		if resp.TargetHostID != serverID {
-			log.Println("sending relay sdp to target host", resp)
-			// relay SDP to target host and get back sdp
-			// TODO: Async
-			sdp := servers[resp.TargetHostID].syncSend(
-				resp,
-			)
-
-			return sdp
-		}
-		log.Println("Target host is overlord itself: start peerconnection")
-		// If the target is in master
-		// start by its old
-		localSession, err := wssession.peerconnection.StartClient(resp.Data, width, height)
-		if err != nil {
-			log.Fatalln(err)
-		}
-
-		return WSPacket{
-			ID:   "sdp",
-			Data: localSession,
-		}
-	})
-
-	// TODO: use relay ID type
-	// TODO: Merge sdp and start
-	client.receive("start", func(resp WSPacket) WSPacket {
-		log.Println("Received a relay start request from a host")
-		// TODO: Abstract
-		if resp.TargetHostID != serverID {
-			// relay SDP to target host and get back sdp
-			// TODO: Async
-			resp := servers[resp.TargetHostID].syncSend(
-				resp,
-			)
-
-			return resp
-		}
-		log.Println("Target host is overlord itself: start game")
-		// If the target is in master
-		// start by its old
-		roomID, isNewRoom := startSession(wssession.peerconnection, resp.Data, resp.RoomID, resp.PlayerIndex)
-		// Bridge always access to old room
-		// TODO: log warn
-		if isNewRoom == true {
-			log.Fatal("Bridge should not spawn new room")
-		}
-
-		return WSPacket{
-			ID:     "start",
-			RoomID: roomID,
-		}
-	})
-
-	client.listen()
-}
diff --git a/overlord/overlord.go b/overlord/overlord.go
index 8b137891..4a9795f8 100644
--- a/overlord/overlord.go
+++ b/overlord/overlord.go
@@ -1 +1,123 @@
+package main
 
+import (
+	"fmt"
+	"log"
+	"math/rand"
+	"net/http"
+	"strconv"
+
+	"github.com/giongto35/cloud-game/webrtc"
+)
+
+var roomToServer = map[string]string{}
+
+// servers are the map serverID to server Client
+var servers = map[string]*Client{}
+
+// If it's overlord, handle overlord connection (from host to overlord)
+func wso(w http.ResponseWriter, r *http.Request) {
+	fmt.Println("Connected")
+	c, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		log.Print("[!] WS upgrade:", err)
+		return
+	}
+	defer c.Close()
+
+	// register new server
+	serverID := strconv.Itoa(rand.Int())
+	log.Println("A new server connected ", serverID)
+
+	client := NewClient(c)
+	servers[serverID] = client
+
+	wssession := &Session{
+		client:         client,
+		peerconnection: webrtc.NewWebRTC(),
+		// The server session is maintaining
+	}
+
+	client.send(
+		WSPacket{
+			ID:   "serverID",
+			Data: serverID,
+		},
+		nil,
+	)
+
+	client.receive("registerRoom", func(resp WSPacket) WSPacket {
+		log.Println("Received registerRoom ", resp.Data, serverID)
+		roomToServer[resp.Data] = serverID
+		return WSPacket{
+			ID: "registerRoom",
+		}
+	})
+
+	client.receive("getRoom", func(resp WSPacket) WSPacket {
+		log.Println("Received a getroom request")
+		return WSPacket{
+			ID:   "getRoom",
+			Data: roomToServer[resp.Data],
+		}
+	})
+
+	client.receive("initwebrtc", func(resp WSPacket) WSPacket {
+		log.Println("Received a relay sdp request from a host")
+		// TODO: Abstract
+		if resp.TargetHostID != serverID {
+			log.Println("sending relay sdp to target host", resp)
+			// relay SDP to target host and get back sdp
+			// TODO: Async
+			sdp := servers[resp.TargetHostID].syncSend(
+				resp,
+			)
+
+			return sdp
+		}
+		log.Println("Target host is overlord itself: start peerconnection")
+		// If the target is in master
+		// start by its old
+		localSession, err := wssession.peerconnection.StartClient(resp.Data, width, height)
+		if err != nil {
+			log.Fatalln(err)
+		}
+
+		return WSPacket{
+			ID:   "sdp",
+			Data: localSession,
+		}
+	})
+
+	// TODO: use relay ID type
+	// TODO: Merge sdp and start
+	client.receive("start", func(resp WSPacket) WSPacket {
+		log.Println("Received a relay start request from a host")
+		// TODO: Abstract
+		if resp.TargetHostID != serverID {
+			// relay SDP to target host and get back sdp
+			// TODO: Async
+			resp := servers[resp.TargetHostID].syncSend(
+				resp,
+			)
+
+			return resp
+		}
+		log.Println("Target host is overlord itself: start game")
+		// If the target is in master
+		// start by its old
+		roomID, isNewRoom := startSession(wssession.peerconnection, resp.Data, resp.RoomID, resp.PlayerIndex)
+		// Bridge always access to old room
+		// TODO: log warn
+		if isNewRoom == true {
+			log.Fatal("Bridge should not spawn new room")
+		}
+
+		return WSPacket{
+			ID:     "start",
+			RoomID: roomID,
+		}
+	})
+
+	client.listen()
+}
diff --git a/nes/apu.go b/ui/nes/apu.go
similarity index 100%
rename from nes/apu.go
rename to ui/nes/apu.go
diff --git a/nes/cartridge.go b/ui/nes/cartridge.go
similarity index 100%
rename from nes/cartridge.go
rename to ui/nes/cartridge.go
diff --git a/nes/console.go b/ui/nes/console.go
similarity index 100%
rename from nes/console.go
rename to ui/nes/console.go
diff --git a/nes/controller.go b/ui/nes/controller.go
similarity index 100%
rename from nes/controller.go
rename to ui/nes/controller.go
diff --git a/nes/cpu.go b/ui/nes/cpu.go
similarity index 100%
rename from nes/cpu.go
rename to ui/nes/cpu.go
diff --git a/nes/filter.go b/ui/nes/filter.go
similarity index 100%
rename from nes/filter.go
rename to ui/nes/filter.go
diff --git a/nes/ines.go b/ui/nes/ines.go
similarity index 100%
rename from nes/ines.go
rename to ui/nes/ines.go
diff --git a/nes/mapper.go b/ui/nes/mapper.go
similarity index 100%
rename from nes/mapper.go
rename to ui/nes/mapper.go
diff --git a/nes/mapper1.go b/ui/nes/mapper1.go
similarity index 100%
rename from nes/mapper1.go
rename to ui/nes/mapper1.go
diff --git a/nes/mapper2.go b/ui/nes/mapper2.go
similarity index 100%
rename from nes/mapper2.go
rename to ui/nes/mapper2.go
diff --git a/nes/mapper225.go b/ui/nes/mapper225.go
similarity index 100%
rename from nes/mapper225.go
rename to ui/nes/mapper225.go
diff --git a/nes/mapper3.go b/ui/nes/mapper3.go
similarity index 100%
rename from nes/mapper3.go
rename to ui/nes/mapper3.go
diff --git a/nes/mapper4.go b/ui/nes/mapper4.go
similarity index 100%
rename from nes/mapper4.go
rename to ui/nes/mapper4.go
diff --git a/nes/mapper7.go b/ui/nes/mapper7.go
similarity index 100%
rename from nes/mapper7.go
rename to ui/nes/mapper7.go
diff --git a/nes/memory.go b/ui/nes/memory.go
similarity index 100%
rename from nes/memory.go
rename to ui/nes/memory.go
diff --git a/nes/palette.go b/ui/nes/palette.go
similarity index 100%
rename from nes/palette.go
rename to ui/nes/palette.go
diff --git a/nes/ppu.go b/ui/nes/ppu.go
similarity index 100%
rename from nes/ppu.go
rename to ui/nes/ppu.go
diff --git a/ws.go b/ws/ws.go
similarity index 100%
rename from ws.go
rename to ws/ws.go