diff --git a/src/net/torvald/terrarum/StateInGame.kt b/src/net/torvald/terrarum/StateInGame.kt
index ed83c048a..fc213576e 100644
--- a/src/net/torvald/terrarum/StateInGame.kt
+++ b/src/net/torvald/terrarum/StateInGame.kt
@@ -58,7 +58,9 @@ constructor() : BasicGameState() {
     lateinit var debugWindow: UIHandler
     lateinit var notifier: UIHandler
 
-    lateinit internal var player: Player
+    lateinit internal var playerWrapper: AnyPlayer
+    internal val player: HistoricalFigure // currently POSSESSED actor :)
+        get() = playerWrapper.actor
 
     //private var GRADIENT_IMAGE: Image? = null
     //private var skyBox: Rectangle? = null
@@ -119,7 +121,7 @@ constructor() : BasicGameState() {
 
 
         // add new player and put it to actorContainer
-        player = PBSigrid.create()
+        playerWrapper = AnyPlayer(PBSigrid.create())
         //player = PBCynthia.create()
         //player.setNoClip(true);
         addActor(player)
@@ -199,6 +201,8 @@ constructor() : BasicGameState() {
         ///////////////////////////
         // actor-related updates //
         ///////////////////////////
+        repossessActor()
+
         // determine whether the inactive actor should be re-active
         wakeDormantActors()
         // determine whether the actor should be active or dormant
@@ -226,6 +230,31 @@ constructor() : BasicGameState() {
         Terrarum.gameConfig["smoothlighting"] = KeyToggler.isOn(KEY_LIGHTMAP_SMOOTH)
     }
 
+    private fun repossessActor() {
+        // check if currently pocessed actor is removed from game
+        if (!hasActor(player))
+            // re-possess canonical player
+            changePossession(Player.PLAYER_REF_ID) // TODO completely other behaviour?
+    }
+
+    private fun changePossession(newActor: AnyPlayer) {
+        if (!hasActor(player)) {
+            throw IllegalArgumentException("No such actor in actorContainer: $newActor")
+        }
+
+        playerWrapper = newActor
+        WorldSimulator(world, player, UPDATE_DELTA)
+    }
+
+    private fun changePossession(refid: Int) {
+        if (!hasActor(refid)) {
+            throw IllegalArgumentException("No such actor in actorContainer: $refid")
+        }
+
+        playerWrapper = AnyPlayer(getActorByID(refid) as HistoricalFigure)
+        WorldSimulator(world, player, UPDATE_DELTA)
+    }
+
     private fun setAppTitle() {
         Terrarum.appgc.setTitle(
                 "${Terrarum.NAME}" +
@@ -319,7 +348,7 @@ constructor() : BasicGameState() {
         }
         // fluidmap debug
         if (KeyToggler.isOn(Key.F4))
-            WorldSimulator.drawFluidMapDebug(player, g)
+            WorldSimulator.drawFluidMapDebug(g)
 
 
         //////////////
@@ -482,7 +511,7 @@ constructor() : BasicGameState() {
 
     fun Double.sqr() = this * this
     fun Int.sqr() = this * this
-    private fun distToActorSqr(a: Visible, p: Player): Double =
+    private fun distToActorSqr(a: Visible, p: ActorWithBody): Double =
             (a.hitbox.centeredX - p.hitbox.centeredX).sqr() + (a.hitbox.centeredY - p.hitbox.centeredY).sqr()
     /** whether the actor is within screen */
     private fun Visible.inScreen() = distToActorSqr(this, player) <=
diff --git a/src/net/torvald/terrarum/gameactors/AIControlled.kt b/src/net/torvald/terrarum/gameactors/AIControlled.kt
index c39a7fb5e..27792ee7d 100644
--- a/src/net/torvald/terrarum/gameactors/AIControlled.kt
+++ b/src/net/torvald/terrarum/gameactors/AIControlled.kt
@@ -3,6 +3,8 @@ package net.torvald.terrarum.gameactors
 import net.torvald.terrarum.gameactors.ai.ActorAI
 
 /**
+ * Note: AI-controlled actor must be 'Controllable'
+ *
  * Created by minjaesong on 16-03-14.
  */
 interface AIControlled {
diff --git a/src/net/torvald/terrarum/gameactors/ActorWithBody.kt b/src/net/torvald/terrarum/gameactors/ActorWithBody.kt
index 44d256546..a548f8692 100644
--- a/src/net/torvald/terrarum/gameactors/ActorWithBody.kt
+++ b/src/net/torvald/terrarum/gameactors/ActorWithBody.kt
@@ -443,8 +443,7 @@ open class ActorWithBody : Actor(), Visible {
             else if (moveDelta.y < 0.0) { // or was moving upward?
                 grounded = false
                 if (isTouchingSide(nextHitbox, COLLIDING_TOP)) { // actor hit something on its top
-                    //hitAndForciblyReflectY()
-                    hitAndReflectY()
+                    hitAndForciblyReflectY() // prevents sticking to the ceiling
                 }
                 else { // the actor is not grounded at all
                 }
@@ -507,7 +506,9 @@ open class ActorWithBody : Actor(), Visible {
         }
     }
 
-    @Deprecated("it's no use!")
+    /**
+     * prevents sticking to the ceiling
+     */
     private fun hitAndForciblyReflectY() {
         if (veloY.abs() * CEILING_HIT_ELASTICITY > A_PIXEL)
             veloY = -veloY * CEILING_HIT_ELASTICITY
@@ -965,7 +966,7 @@ open class ActorWithBody : Actor(), Visible {
     private fun assertInit() {
         // errors
         if (baseHitboxW == 0 || baseHitboxH == 0)
-            throw RuntimeException("Hitbox dimension was not set.")
+            throw Error("Hitbox dimension was not set.")
 
         // warnings
         if (sprite == null && isVisible)
diff --git a/src/net/torvald/terrarum/gameactors/AnyPlayer.kt b/src/net/torvald/terrarum/gameactors/AnyPlayer.kt
new file mode 100644
index 000000000..3ea7a7108
--- /dev/null
+++ b/src/net/torvald/terrarum/gameactors/AnyPlayer.kt
@@ -0,0 +1,23 @@
+package net.torvald.terrarum.gameactors
+
+import org.newdawn.slick.Input
+
+/**
+ * Created by minjaesong on 16-10-23.
+ */
+class AnyPlayer(val actor: HistoricalFigure) {
+
+    init {
+        if (actor !is Controllable)
+            throw IllegalArgumentException("Player must be 'Controllable'!")
+    }
+
+    fun processInput(input: Input) {
+        (actor as Controllable).processInput(input)
+    }
+
+    fun keyPressed(key: Int, c: Char) {
+        (actor as Controllable).keyPressed(key, c)
+    }
+
+}
\ No newline at end of file
diff --git a/src/net/torvald/terrarum/gameactors/HistoricalFigure.kt b/src/net/torvald/terrarum/gameactors/HistoricalFigure.kt
index 877f5f33e..9253c2e01 100644
--- a/src/net/torvald/terrarum/gameactors/HistoricalFigure.kt
+++ b/src/net/torvald/terrarum/gameactors/HistoricalFigure.kt
@@ -1,14 +1,17 @@
 package net.torvald.terrarum.gameactors
 
 import net.torvald.terrarum.gameworld.WorldTime
+import org.newdawn.slick.Input
 
 /**
  * An actor (NPC) which has life and death,
  * though death might not exist if it has achieved immortality :)
  *
+ * NOTE: all canonical NPCs are must be HistoricalFigure!! (double excl mark, bitch)
+ *
  * Created by minjaesong on 16-10-10.
  */
-open class HistoricalFigure(born: GameDate, dead: GameDate? = null) : ActorWithBody() {
+open class HistoricalFigure(val born: GameDate, val dead: GameDate? = null) : ActorWithBody(), Controllable {
 
     init {
         this.actorValue["_bornyear"] = born.year
@@ -20,6 +23,21 @@ open class HistoricalFigure(born: GameDate, dead: GameDate? = null) : ActorWithB
         }
     }
 
+    override fun processInput(input: Input) {
+        // let out children play
+    }
+
+    override fun keyPressed(key: Int, c: Char) {
+        // let out children play
+    }
+
+    open internal var noClip = false
+
+    open fun isNoClip() = noClip
+
+    open fun setNoClip(b: Boolean) {
+        noClip = b
+    }
 }
 
 data class GameDate(val year: Int, val yearlyDay: Int) {
diff --git a/src/net/torvald/terrarum/gameactors/PBSigrid.kt b/src/net/torvald/terrarum/gameactors/PBSigrid.kt
index 0bb5ae414..8e6667274 100644
--- a/src/net/torvald/terrarum/gameactors/PBSigrid.kt
+++ b/src/net/torvald/terrarum/gameactors/PBSigrid.kt
@@ -46,7 +46,7 @@ object PBSigrid {
          * fixed value, or 'base value', from creature strength of Dwarf Fortress.
          * Human race uses 1000. (see CreatureHuman.json)
          */
-        p.actorValue[AVKey.STRENGTH] = 1414
+        p.actorValue[AVKey.STRENGTH] = 1414 // this is test character, after all.
         p.actorValue[AVKey.ENCUMBRANCE] = 1000
         p.actorValue[AVKey.BASEHEIGHT] = 46
 
@@ -59,8 +59,8 @@ object PBSigrid {
         p.actorValue[AVKey.BASEDEFENCE] = 141
 
         p.actorValue[AVKey.__PLAYER_QUICKBARSEL] = 0
-        p.actorValue["__selectedtile"] = 16 // test code; replace with <tile_item>.primaryUse(gc, delta)
-        p.actorValue["__aimhelper"] = true
+        p.actorValue["__selectedtile"] = 147 // test code; replace with <tile_item>.primaryUse(gc, delta)
+        p.actorValue["__aimhelper"] = true // TODO when you'll gonna implement it?
 
         p.setHitboxDimension(15, p.actorValue.getAsInt(AVKey.BASEHEIGHT)!!, 10, 0)
 
diff --git a/src/net/torvald/terrarum/gameactors/Player.kt b/src/net/torvald/terrarum/gameactors/Player.kt
index 79c323274..8a1b6d1d1 100644
--- a/src/net/torvald/terrarum/gameactors/Player.kt
+++ b/src/net/torvald/terrarum/gameactors/Player.kt
@@ -16,6 +16,8 @@ import org.newdawn.slick.SlickException
 import java.util.*
 
 /**
+ * Game player (YOU!)
+ *
  * Created by minjaesong on 16-03-14.
  */
 
@@ -53,7 +55,7 @@ class Player(born: GameDate) : HistoricalFigure(born), Controllable, Pocketed, F
     @Transient private var prevHMoveKey = KEY_NULL
     @Transient private var prevVMoveKey = KEY_NULL
 
-    internal var noClip = false
+    override internal var noClip = false
 
     @Transient private val AXIS_POSMAX = 1.0f
     @Transient private val GAMEPAD_JUMP = 7
@@ -491,11 +493,11 @@ class Player(born: GameDate) : HistoricalFigure(born), Controllable, Pocketed, F
         }
     }
 
-    fun isNoClip(): Boolean {
+    override fun isNoClip(): Boolean {
         return noClip
     }
 
-    fun setNoClip(b: Boolean) {
+    override fun setNoClip(b: Boolean) {
         noClip = b
     }
 
diff --git a/src/net/torvald/terrarum/gameactors/PlayerBuilder.kt b/src/net/torvald/terrarum/gameactors/PlayerBuilder.kt
index 77f6161ad..eba8c93cb 100644
--- a/src/net/torvald/terrarum/gameactors/PlayerBuilder.kt
+++ b/src/net/torvald/terrarum/gameactors/PlayerBuilder.kt
@@ -11,9 +11,8 @@ object PlayerBuilder {
     private val JSONPATH = "./assets/raw/"
     private val jsonString = String()
 
-    @Throws(IOException::class, SlickException::class)
-    fun create(): Player {
-        val p: Player = Player(Terrarum.ingame.world.time.currentTimeAsGameDate)
+    fun create(): Actor {
+        val p: Actor = Player(Terrarum.ingame.world.time.currentTimeAsGameDate)
         CreatureRawInjector.inject(p.actorValue, "CreatureHuman.json")
 
         // attach sprite
diff --git a/src/net/torvald/terrarum/gamecontroller/GameController.kt b/src/net/torvald/terrarum/gamecontroller/GameController.kt
index 54758a3a2..46b75e131 100644
--- a/src/net/torvald/terrarum/gamecontroller/GameController.kt
+++ b/src/net/torvald/terrarum/gamecontroller/GameController.kt
@@ -32,8 +32,8 @@ object GameController {
 
 
         if (!Terrarum.ingame.consoleHandler.isTakingControl) {
-            if (Terrarum.ingame.player.vehicleRiding != null) {
-                Terrarum.ingame.player.vehicleRiding!!.processInput(input)
+            if (Terrarum.ingame.player is Player && (Terrarum.ingame.player as Player).vehicleRiding != null) {
+                (Terrarum.ingame.player as Player).vehicleRiding!!.processInput(input)
             }
 
             Terrarum.ingame.player.processInput(input)
@@ -83,8 +83,8 @@ object GameController {
 
 
         if (!Terrarum.ingame.consoleHandler.isTakingControl) {
-            if (Terrarum.ingame.player.vehicleRiding != null) {
-                Terrarum.ingame.player.vehicleRiding!!.keyPressed(key, c)
+            if (Terrarum.ingame.player is Player && (Terrarum.ingame.player as Player).vehicleRiding != null) {
+                (Terrarum.ingame.player as Player).vehicleRiding!!.keyPressed(key, c)
             }
 
             Terrarum.ingame.player.keyPressed(key, c)
diff --git a/src/net/torvald/terrarum/gameworld/WorldSimulator.kt b/src/net/torvald/terrarum/gameworld/WorldSimulator.kt
index 0751dea06..431a51b7e 100644
--- a/src/net/torvald/terrarum/gameworld/WorldSimulator.kt
+++ b/src/net/torvald/terrarum/gameworld/WorldSimulator.kt
@@ -2,6 +2,7 @@ package net.torvald.terrarum.gameworld
 
 import net.torvald.random.HQRNG
 import net.torvald.terrarum.Terrarum
+import net.torvald.terrarum.gameactors.HistoricalFigure
 import net.torvald.terrarum.gameactors.Player
 import net.torvald.terrarum.gameactors.roundInt
 import net.torvald.terrarum.gameworld.WorldSimulator.isSolid
@@ -37,14 +38,15 @@ object WorldSimulator {
     val colourNone = Color(0x808080)
     val colourWater = Color(0x66BBFF)
 
-    operator fun invoke(world: GameWorld, p: Player, delta: Int) {
+    // TODO future Kotlin feature -- typealias AnyPlayer: HistoricalFigure
+    operator fun invoke(world: GameWorld, p: HistoricalFigure, delta: Int) {
         updateXFrom = p.hitbox.centeredX.div(MapDrawer.TILE_SIZE).minus(FLUID_UPDATING_SQUARE_RADIUS).roundInt()
         updateYFrom = p.hitbox.centeredY.div(MapDrawer.TILE_SIZE).minus(FLUID_UPDATING_SQUARE_RADIUS).roundInt()
         updateXTo = updateXFrom + DOUBLE_RADIUS
         updateYTo = updateYFrom + DOUBLE_RADIUS
 
-        moveFluids(world, p, delta)
-        displaceFallables(world, p, delta)
+        moveFluids(world, delta)
+        displaceFallables(world, delta)
     }
 
     /**
@@ -52,7 +54,7 @@ object WorldSimulator {
      * which means you'll need to modify the code A LOT if you're going to implement zero- or
      * reverse-gravity.
      */
-    fun moveFluids(world: GameWorld, p: Player, delta: Int) {
+    fun moveFluids(world: GameWorld, delta: Int) {
         ////////////////////
         // build fluidmap //
         ////////////////////
@@ -121,7 +123,7 @@ object WorldSimulator {
      * displace fallable tiles. It is scanned bottom-left first. To achieve the sens ofreal
      * falling, each tiles are displaced by ONLY ONE TILE below.
      */
-    fun displaceFallables(world: GameWorld, p: Player, delta: Int) {
+    fun displaceFallables(world: GameWorld, delta: Int) {
         for (y in updateYFrom..updateYTo) {
             for (x in updateXFrom..updateXTo) {
                 val tile = world.getTileFromTerrain(x, y) ?: TileNameCode.STONE
@@ -146,7 +148,7 @@ object WorldSimulator {
         }
     }
 
-    fun drawFluidMapDebug(p: Player, g: Graphics) {
+    fun drawFluidMapDebug(g: Graphics) {
         g.font = Terrarum.fontSmallNumbers
         g.color = colourWater
 
diff --git a/src/net/torvald/terrarum/ui/BasicDebugInfoWindow.kt b/src/net/torvald/terrarum/ui/BasicDebugInfoWindow.kt
index 9ed2f5ed7..041335c75 100644
--- a/src/net/torvald/terrarum/ui/BasicDebugInfoWindow.kt
+++ b/src/net/torvald/terrarum/ui/BasicDebugInfoWindow.kt
@@ -100,7 +100,7 @@ class BasicDebugInfoWindow : UICanvas {
         printLine(g, 5, "grounded $ccG${player.grounded}")
         printLine(g, 6, "noClip $ccG${player.noClip}")
 
-        printLine(g, 7, "jump $ccG${player.jumpAcc}")
+        //printLine(g, 7, "jump $ccG${player.jumpAcc}")
 
         val lightVal: String
         val mtX = mouseTileX.toString()
diff --git a/src/net/torvald/terrarum/ui/UIQuickBar.kt b/src/net/torvald/terrarum/ui/UIQuickBar.kt
index 6eb790a15..2bacc54d9 100644
--- a/src/net/torvald/terrarum/ui/UIQuickBar.kt
+++ b/src/net/torvald/terrarum/ui/UIQuickBar.kt
@@ -24,7 +24,7 @@ class UIQuickBar : UICanvas, MouseControlled {
     override var handler: UIHandler? = null
 
     private var selection: Int
-        get() = Terrarum.ingame.player.actorValue.getAsInt(AVKey.__PLAYER_QUICKBARSEL)!!
+        get() = Terrarum.ingame.player.actorValue.getAsInt(AVKey.__PLAYER_QUICKBARSEL) ?: 0
         set(value) { Terrarum.ingame.player.actorValue[AVKey.__PLAYER_QUICKBARSEL] = value }
 
     override fun update(gc: GameContainer, delta: Int) {