diff --git a/.idea/vcs.xml b/.idea/vcs.xml
new file mode 100644
index 0000000..94a25f7
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/build.gradle.kts b/build.gradle.kts
index 8fd8070..1057326 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -1,3 +1,5 @@
+import org.jetbrains.kotlin.util.capitalizeDecapitalize.toLowerCaseAsciiOnly
+
 plugins {
     kotlin("jvm") version "1.8.0"
     application
@@ -6,7 +8,7 @@ plugins {
 group = "dev.jombi"
 version = "1.0-DEV"
 val lwjglVersion = "3.3.1"
-val lwjglNatives = "natives-macos-arm64"
+val natives = arrayOf("natives-windows", "natives-macos-arm64")
 
 repositories {
     mavenCentral()
@@ -21,12 +23,33 @@ dependencies {
     implementation("org.lwjgl", "lwjgl-openal")
     implementation("org.lwjgl", "lwjgl-opengl")
     implementation("org.lwjgl", "lwjgl-stb")
-    runtimeOnly("org.lwjgl", "lwjgl", classifier = lwjglNatives)
-    runtimeOnly("org.lwjgl", "lwjgl-assimp", classifier = lwjglNatives)
-    runtimeOnly("org.lwjgl", "lwjgl-glfw", classifier = lwjglNatives)
-    runtimeOnly("org.lwjgl", "lwjgl-openal", classifier = lwjglNatives)
-    runtimeOnly("org.lwjgl", "lwjgl-opengl", classifier = lwjglNatives)
-    runtimeOnly("org.lwjgl", "lwjgl-stb", classifier = lwjglNatives)
+
+    natives.forEach {
+        runtimeOnly("org.lwjgl", "lwjgl", classifier = it)
+        runtimeOnly("org.lwjgl", "lwjgl-assimp", classifier = it)
+        runtimeOnly("org.lwjgl", "lwjgl-glfw", classifier = it)
+        runtimeOnly("org.lwjgl", "lwjgl-openal", classifier = it)
+        runtimeOnly("org.lwjgl", "lwjgl-opengl", classifier = it)
+        runtimeOnly("org.lwjgl", "lwjgl-stb", classifier = it)
+    }
+}
+
+val fatJar = task("fatJar", type = Jar::class) {
+    archiveFileName.set("${project.name.toLowerCaseAsciiOnly()}.jar")
+    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
+    manifest {
+        attributes["Implementation-Title"] = "Gradle Jar File Example"
+        attributes["Implementation-Version"] = archiveVersion.get()
+        attributes["Main-Class"] = "dev.jombi.tetris.MainKt"
+    }
+    from(configurations.runtimeClasspath.get().map { if (it.isDirectory) it else zipTree(it) })
+    with(tasks.jar.get() as CopySpec)
+}
+
+tasks {
+    "build" {
+        dependsOn(fatJar)
+    }
 }
 
 tasks.test {
@@ -38,5 +61,5 @@ kotlin {
 }
 
 application {
-    mainClass.set("MainKt")
+    mainClass.set("dev.jombi.tetris.MainKt")
 }
\ No newline at end of file
diff --git a/src/main/kotlin/dev/jombi/tetris/Field.kt b/src/main/kotlin/dev/jombi/tetris/Field.kt
index 0b35c9c..4312d55 100644
--- a/src/main/kotlin/dev/jombi/tetris/Field.kt
+++ b/src/main/kotlin/dev/jombi/tetris/Field.kt
@@ -110,6 +110,7 @@ class Field {
     var currentMino: Tetrimino? = null
     var minoPosY = 0
         set(value) {
+            if (currentMino == null) return
             if (field == value) return
             if (value in -2 until blockY && !checkFloor(currentMino!!, minoSpin, value)) {
                 field = value
@@ -237,8 +238,8 @@ class Field {
                     currentMino = null
                 }
             } catch (e: ArrayIndexOutOfBoundsException) {
-                GLTetrisGame.instance().displayScreen(GuiGameOver())
-                GLTetrisGame.instance().finalizeGame()
+                GLTetrisGame.getInstance().displayScreen(GuiGameOver())
+                GLTetrisGame.getInstance().finalizeGame()
                 System.gc()
             }
     }
diff --git a/src/main/kotlin/dev/jombi/tetris/GLTetrisGame.kt b/src/main/kotlin/dev/jombi/tetris/GLTetrisGame.kt
index c723a8c..afa6aaf 100644
--- a/src/main/kotlin/dev/jombi/tetris/GLTetrisGame.kt
+++ b/src/main/kotlin/dev/jombi/tetris/GLTetrisGame.kt
@@ -10,17 +10,17 @@ import org.lwjgl.glfw.GLFWErrorCallback
 import org.lwjgl.opengl.GL
 import org.lwjgl.opengl.GL11.*
 import org.lwjgl.system.MemoryUtil.NULL
-import kotlin.properties.Delegates
 
 class GLTetrisGame {
     companion object {
         private val instance = GLTetrisGame()
-        fun instance() = instance
+        @JvmStatic
+        fun getInstance() = instance
     }
 
     private val gameTimer = Timer(20.0f, 0L)
     private val keyTimer = Timer(40.0f, 0)
-    private var window by Delegates.notNull<Long>()
+    private var window  = 0L
     private var field: Field? = null
     val WIDTH = 400
     val HEIGHT = 490
@@ -170,9 +170,10 @@ class GLTetrisGame {
     }
 
     fun clear() {
-        glfwFreeCallbacks(window)
-        glfwDestroyWindow(window)
-
+        if (window != 0L) {
+            glfwFreeCallbacks(window)
+            glfwDestroyWindow(window)
+        }
         glfwTerminate()
         glfwSetErrorCallback(null)?.free()
     }
diff --git a/src/main/kotlin/dev/jombi/tetris/Main.kt b/src/main/kotlin/dev/jombi/tetris/Main.kt
index b70e7ce..b546cfd 100644
--- a/src/main/kotlin/dev/jombi/tetris/Main.kt
+++ b/src/main/kotlin/dev/jombi/tetris/Main.kt
@@ -1,10 +1,15 @@
 package dev.jombi.tetris
 
+import java.lang.Exception
+
 fun main() {
-    val tetrKt = GLTetrisGame.instance()
+    val tetrKt = GLTetrisGame.getInstance()
     try {
         tetrKt.init()
         tetrKt.loop()
+    } catch (e: Exception) {
+        e.printStackTrace()
+        println("Error while loop.")
     } finally {
         tetrKt.clear()
     }
diff --git a/src/main/kotlin/dev/jombi/tetris/screen/impl/GuiGameOver.kt b/src/main/kotlin/dev/jombi/tetris/screen/impl/GuiGameOver.kt
index 874e227..51fb71a 100644
--- a/src/main/kotlin/dev/jombi/tetris/screen/impl/GuiGameOver.kt
+++ b/src/main/kotlin/dev/jombi/tetris/screen/impl/GuiGameOver.kt
@@ -6,15 +6,15 @@ import dev.jombi.tetris.screen.overlay.Button
 
 class GuiGameOver : GuiScreen() {
     override fun initGui() {
-        val halfWidth = GLTetrisGame.instance().WIDTH / 2.0
-        val halfHeight = GLTetrisGame.instance().HEIGHT / 2.0
+        val halfWidth = GLTetrisGame.getInstance().WIDTH / 2.0
+        val halfHeight = GLTetrisGame.getInstance().HEIGHT / 2.0
         buttons.add(Button("Retry", halfWidth, halfHeight) {
-            GLTetrisGame.instance().initGame()
-            GLTetrisGame.instance().displayScreen(null)
+            GLTetrisGame.getInstance().initGame()
+            GLTetrisGame.getInstance().displayScreen(null)
         })
 
         buttons.add(Button("Main menu", halfWidth, halfHeight + 40.0) {
-            GLTetrisGame.instance().displayScreen(GuiMainMenu.getInstance())
+            GLTetrisGame.getInstance().displayScreen(GuiMainMenu.getInstance())
         })
     }
 
diff --git a/src/main/kotlin/dev/jombi/tetris/screen/impl/GuiMainMenu.kt b/src/main/kotlin/dev/jombi/tetris/screen/impl/GuiMainMenu.kt
index 065b0aa..8620258 100644
--- a/src/main/kotlin/dev/jombi/tetris/screen/impl/GuiMainMenu.kt
+++ b/src/main/kotlin/dev/jombi/tetris/screen/impl/GuiMainMenu.kt
@@ -17,14 +17,14 @@ class GuiMainMenu private constructor() : GuiScreen() {
         fun getInstance() = instance
     }
     override fun initGui() {
-        val halfWidth = GLTetrisGame.instance().WIDTH / 2.0
-        val halfHeight = GLTetrisGame.instance().HEIGHT / 2.0
+        val halfWidth = GLTetrisGame.getInstance().WIDTH / 2.0
+        val halfHeight = GLTetrisGame.getInstance().HEIGHT / 2.0
         buttons.add(Button("Start", halfWidth, halfHeight) {
-            GLTetrisGame.instance().initGame()
-            GLTetrisGame.instance().displayScreen(null)
+            GLTetrisGame.getInstance().initGame()
+            GLTetrisGame.getInstance().displayScreen(null)
         })
         buttons.add(Button("Exit", halfWidth, halfHeight + 40.0) {
-            GLTetrisGame.instance().exitGame()
+            GLTetrisGame.getInstance().exitGame()
         })
     }
 
@@ -34,7 +34,7 @@ class GuiMainMenu private constructor() : GuiScreen() {
 
     override fun drawScreen(mouseX: Double, mouseY: Double) {
         super.drawScreen(mouseX, mouseY)
-        val halfWidth = GLTetrisGame.instance().WIDTH / 2.0
+        val halfWidth = GLTetrisGame.getInstance().WIDTH / 2.0
         val TARGET_FONT = FontFactory.getFont(FontType.ARIAL, 48)
         val (fWidth, fHeight) = TARGET_FONT.getStringBound("TetrKt")