diff --git a/src/net/torvald/terrarum/console/GetTime.kt b/src/net/torvald/terrarum/console/GetTime.kt
index db82be081..7e6eb3dcf 100644
--- a/src/net/torvald/terrarum/console/GetTime.kt
+++ b/src/net/torvald/terrarum/console/GetTime.kt
@@ -9,10 +9,7 @@ class GetTime : ConsoleCommand {
     override fun execute(args: Array<String>) {
         val echo = Echo()
         val worldTime = Terrarum.ingame.world.time
-        echo.execute("Year ${worldTime.years}, Month ${worldTime.months}, " +
-                     "Day ${worldTime.days} (${worldTime.getDayNameShort()}), " +
-                     "${worldTime.getFormattedTime()}"
-        )
+        echo.execute(worldTime.getFormattedTime())
     }
 
     override fun printUsage() {
diff --git a/src/net/torvald/terrarum/gameactors/ActorWithBody.kt b/src/net/torvald/terrarum/gameactors/ActorWithBody.kt
index 2054ba128..fa167c994 100644
--- a/src/net/torvald/terrarum/gameactors/ActorWithBody.kt
+++ b/src/net/torvald/terrarum/gameactors/ActorWithBody.kt
@@ -130,8 +130,8 @@ open class ActorWithBody : Actor(), Visible {
      */
 
 
-    var grounded = false
-    override var flagDespawn = false
+    @Volatile var grounded = false
+    override @Volatile var flagDespawn = false
     /** Default to 'false'  */
     var isVisible = false
     /** Default to 'true'  */
@@ -146,7 +146,7 @@ open class ActorWithBody : Actor(), Visible {
      * think of a grass cutting on the Zelda games. It would also make a great puzzle to solve.
      * --minjaesong)
      */
-    var isChronostasis = false
+    @Volatile var isChronostasis = false
 
     /**
      * Constants
@@ -213,8 +213,8 @@ open class ActorWithBody : Actor(), Visible {
     @Transient private var assertPrinted = false
 
     // to use with Controller (incl. player)
-    internal var walledLeft = false
-    internal var walledRight = false
+    internal @Volatile var walledLeft = false
+    internal @Volatile var walledRight = false
 
     /**
      * true: This actor had just made collision
diff --git a/src/net/torvald/terrarum/gameactors/HistoricalFigure.kt b/src/net/torvald/terrarum/gameactors/HistoricalFigure.kt
new file mode 100644
index 000000000..877f5f33e
--- /dev/null
+++ b/src/net/torvald/terrarum/gameactors/HistoricalFigure.kt
@@ -0,0 +1,49 @@
+package net.torvald.terrarum.gameactors
+
+import net.torvald.terrarum.gameworld.WorldTime
+
+/**
+ * An actor (NPC) which has life and death,
+ * though death might not exist if it has achieved immortality :)
+ *
+ * Created by minjaesong on 16-10-10.
+ */
+open class HistoricalFigure(born: GameDate, dead: GameDate? = null) : ActorWithBody() {
+
+    init {
+        this.actorValue["_bornyear"] = born.year
+        this.actorValue["_borndays"] = born.yearlyDay
+
+        if (dead != null) {
+            this.actorValue["_deadyear"] = dead.year
+            this.actorValue["_deaddays"] = dead.yearlyDay
+        }
+    }
+
+}
+
+data class GameDate(val year: Int, val yearlyDay: Int) {
+    operator fun plus(other: GameDate): GameDate {
+        var newyd = this.yearlyDay + other.yearlyDay
+        var newy = this.year + other.year
+
+        if (newyd > WorldTime.YEAR_DAYS) {
+            newyd -= WorldTime.YEAR_DAYS
+            newy += 1
+        }
+
+        return GameDate(newy, newyd)
+    }
+
+    operator fun minus(other: GameDate): GameDate {
+        var newyd = this.yearlyDay - other.yearlyDay
+        var newy = this.year - other.year
+
+        if (newyd < 0) {
+            newyd += WorldTime.YEAR_DAYS
+            newy -= 1
+        }
+
+        return GameDate(newy, newyd)
+    }
+}
\ No newline at end of file
diff --git a/src/net/torvald/terrarum/gameactors/NPCIntelligentBase.kt b/src/net/torvald/terrarum/gameactors/NPCIntelligentBase.kt
index 629f12edc..5c5ed8195 100644
--- a/src/net/torvald/terrarum/gameactors/NPCIntelligentBase.kt
+++ b/src/net/torvald/terrarum/gameactors/NPCIntelligentBase.kt
@@ -10,7 +10,7 @@ import java.util.*
 /**
  * Created by minjaesong on 16-03-14.
  */
-open class NPCIntelligentBase : ActorWithBody()
+open class NPCIntelligentBase(born: GameDate) : HistoricalFigure(born)
         , AIControlled, Pocketed, CanBeAnItem, Factionable, LandHolder {
 
     override var actorAI: ActorAI = object : ActorAI {
diff --git a/src/net/torvald/terrarum/gameactors/PBCynthia.kt b/src/net/torvald/terrarum/gameactors/PBCynthia.kt
index 0f03e1317..56bc1b5c9 100644
--- a/src/net/torvald/terrarum/gameactors/PBCynthia.kt
+++ b/src/net/torvald/terrarum/gameactors/PBCynthia.kt
@@ -9,7 +9,7 @@ import net.torvald.terrarum.mapdrawer.MapDrawer
 object PBCynthia {
 
     fun create(): Player {
-        val p: Player = Player()
+        val p: Player = Player(GameDate(100, 143)) // random value thrown
         CreatureRawInjector.inject(p.actorValue, "CreatureHuman.json")
 
         p.actorValue[AVKey.__PLAYER_QUICKBARSEL] = 0
diff --git a/src/net/torvald/terrarum/gameactors/PBSigrid.kt b/src/net/torvald/terrarum/gameactors/PBSigrid.kt
index e2f1201d9..0bb5ae414 100644
--- a/src/net/torvald/terrarum/gameactors/PBSigrid.kt
+++ b/src/net/torvald/terrarum/gameactors/PBSigrid.kt
@@ -16,7 +16,7 @@ import java.io.IOException
 object PBSigrid {
 
     fun create(): Player {
-        val p = Player()
+        val p = Player(GameDate(-2147483648, 0)) // XD
 
         p.sprite = SpriteAnimation()
         p.sprite!!.setDimension(28, 51)
diff --git a/src/net/torvald/terrarum/gameactors/Player.kt b/src/net/torvald/terrarum/gameactors/Player.kt
index f465091fa..79c323274 100644
--- a/src/net/torvald/terrarum/gameactors/Player.kt
+++ b/src/net/torvald/terrarum/gameactors/Player.kt
@@ -19,7 +19,7 @@ import java.util.*
  * Created by minjaesong on 16-03-14.
  */
 
-class Player : ActorWithBody(), Controllable, Pocketed, Factionable, Luminous, LandHolder {
+class Player(born: GameDate) : HistoricalFigure(born), Controllable, Pocketed, Factionable, Luminous, LandHolder {
 
     /**
      * empirical value.
diff --git a/src/net/torvald/terrarum/gameworld/MapLayer.kt b/src/net/torvald/terrarum/gameworld/MapLayer.kt
index a00d5f496..87d83c1d2 100644
--- a/src/net/torvald/terrarum/gameworld/MapLayer.kt
+++ b/src/net/torvald/terrarum/gameworld/MapLayer.kt
@@ -3,9 +3,9 @@ package net.torvald.terrarum.gameworld
 /**
  * Created by minjaesong on 16-01-17.
  */
-class MapLayer(var width: Int, var height: Int) : Iterable<Byte> {
+class MapLayer(val width: Int, val height: Int) : Iterable<Byte> {
 
-    internal var data: Array<ByteArray>
+    internal @Volatile var data: Array<ByteArray> // in parallel programming: do not trust your register; always read freshly from RAM!
 
     init {
         data = Array(height) { ByteArray(width) }
diff --git a/src/net/torvald/terrarum/gameworld/PairedMapLayer.kt b/src/net/torvald/terrarum/gameworld/PairedMapLayer.kt
index 91790b998..19d10d5d6 100644
--- a/src/net/torvald/terrarum/gameworld/PairedMapLayer.kt
+++ b/src/net/torvald/terrarum/gameworld/PairedMapLayer.kt
@@ -7,7 +7,7 @@ import java.util.function.Consumer
 /**
  * Created by minjaesong on 16-02-15.
  */
-class PairedMapLayer(width: Int, var height: Int) : Iterable<Byte> {
+class PairedMapLayer(width: Int, val height: Int) : Iterable<Byte> {
 
     /**
      * 0b_xxxx_yyyy, x for lower index, y for higher index
@@ -17,9 +17,9 @@ class PairedMapLayer(width: Int, var height: Int) : Iterable<Byte> {
      * 0110 1101 is interpreted as
      * 6 for tile 0, 13 for tile 1.
      */
-    internal var dataPair: Array<ByteArray>
+    internal @Volatile var dataPair: Array<ByteArray>
 
-    var width: Int = 0
+    val width: Int
 
     init {
         this.width = width / 2
diff --git a/src/net/torvald/terrarum/gameworld/WorldTime.kt b/src/net/torvald/terrarum/gameworld/WorldTime.kt
index 5ee501345..efa2391dd 100644
--- a/src/net/torvald/terrarum/gameworld/WorldTime.kt
+++ b/src/net/torvald/terrarum/gameworld/WorldTime.kt
@@ -56,6 +56,8 @@ class WorldTime {
         val HOUR_MIN: Int = 60
         val GAME_MIN_TO_REAL_SEC: Float = 60f
 
+        val YEAR_DAYS: Int = 365
+
         fun parseTime(s: String): Int =
                 if (s.length >= 4) {
                     s.toLowerCase().substringBefore('h').toInt() * WorldTime.HOUR_SEC +
@@ -103,9 +105,6 @@ class WorldTime {
     val elapsedSeconds: Int
         get() = (HOUR_SEC * hours + MINUTE_SEC * minutes + seconds) % DAY_LENGTH
 
-    val isLeapYear: Boolean
-        get() = years % 4 == 0 && years % 100 != 0 || years % 400 == 0
-
     /** Sets time of this day. */
     fun setTime(t: Int) {
         days += t / DAY_LENGTH
@@ -148,11 +147,11 @@ class WorldTime {
         if (dayOfWeek == 7) {
             dayOfWeek = 0
         }
-        if ((months == 12 || months == 7 && isLeapYear) && days == 31) {
+        if (months == 12 && days == 31) {
             dayOfWeek = 7
         }
 
-        if ((months == 12 || months == 7 && isLeapYear) && days == 32) {
+        if (months == 12 && days == 32) {
             days = 1
             months = 1
             years++
@@ -173,7 +172,14 @@ class WorldTime {
         }
     }
 
-    fun getFormattedTime() = "${String.format("%02d", hours)}h${String.format("%02d", minutes)}"
+    /** Format: "%A %d %B %Y %X" */
+    fun getFormattedTime() = "${getDayNameFull()} " +
+                             "$days " +
+                             "${getMonthNameFull()} " +
+                             "$years " +
+                             "${String.format("%02d", hours)}:" +
+                             "${String.format("%02d", minutes)}:" +
+                             "${String.format("%02d", seconds)}"
 
     fun getDayNameFull() = DAY_NAMES[dayOfWeek]
     fun getDayNameShort() = DAY_NAMES_SHORT[dayOfWeek]
diff --git a/src/net/torvald/terrarum/virtualcomputer/assets/lua/BOOT.lua b/src/net/torvald/terrarum/virtualcomputer/assets/lua/BOOT.lua
index eaf6ceda0..324282f18 100644
--- a/src/net/torvald/terrarum/virtualcomputer/assets/lua/BOOT.lua
+++ b/src/net/torvald/terrarum/virtualcomputer/assets/lua/BOOT.lua
@@ -455,7 +455,7 @@ do
             end
         ::brk::
         end
-    return s
+        return s
     end
 
     local function push_onecapture(ms, i, s, e)
diff --git a/src/org/dyn4j/geometry/Vector2.kt b/src/org/dyn4j/geometry/Vector2.kt
index 114a4b664..3a5890718 100644
--- a/src/org/dyn4j/geometry/Vector2.kt
+++ b/src/org/dyn4j/geometry/Vector2.kt
@@ -66,10 +66,10 @@ import org.dyn4j.Epsilon
 class Vector2 {
 
     /** The magnitude of the x component of this [Vector2]  */
-    var x: Double = 0.0
+    @Volatile var x: Double = 0.0
 
     /** The magnitude of the y component of this [Vector2]  */
-    var y: Double = 0.0
+    @Volatile var y: Double = 0.0
 
     /** Default constructor.  */
     constructor() {