diff --git a/.idea/caches/build_file_checksums.ser b/.idea/caches/build_file_checksums.ser
index f704e9b..47d3077 100644
Binary files a/.idea/caches/build_file_checksums.ser and b/.idea/caches/build_file_checksums.ser differ
diff --git a/app/src/main/java/adrienmalin/pingpoints/CreditsActivity.kt b/app/src/main/java/adrienmalin/pingpoints/CreditsActivity.kt
index f7564b8..e16cd37 100644
--- a/app/src/main/java/adrienmalin/pingpoints/CreditsActivity.kt
+++ b/app/src/main/java/adrienmalin/pingpoints/CreditsActivity.kt
@@ -1,9 +1,12 @@
 package adrienmalin.pingpoints
 
-import android.content.Intent
 import android.support.v7.app.AppCompatActivity
 import android.os.Bundle
 import android.view.MenuItem
+import android.text.method.LinkMovementMethod
+import android.widget.TextView
+
+
 
 class CreditsActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -11,6 +14,7 @@ class CreditsActivity : AppCompatActivity() {
         setContentView(R.layout.activity_credits)
         setSupportActionBar(findViewById(R.id.toolbar))
         supportActionBar?.setDisplayHomeAsUpEnabled(true)
+        findViewById<TextView>(R.id.iconsCredit)?.movementMethod = LinkMovementMethod.getInstance()
     }
 
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
diff --git a/app/src/main/java/adrienmalin/pingpoints/MainActivity.kt b/app/src/main/java/adrienmalin/pingpoints/MainActivity.kt
index 3d57cd2..a96b926 100644
--- a/app/src/main/java/adrienmalin/pingpoints/MainActivity.kt
+++ b/app/src/main/java/adrienmalin/pingpoints/MainActivity.kt
@@ -8,6 +8,7 @@ import android.view.View
 import android.widget.Button
 import android.os.Build
 import android.support.v7.app.AppCompatDelegate
+import android.support.v7.view.menu.ActionMenuItem
 import android.view.Menu
 import android.widget.Toast
 import android.view.MenuItem
@@ -22,8 +23,10 @@ class MainActivity : AppCompatActivity(), StarterNameDialog.StarterNameDialogLis
     var textService: android.widget.TextView? = null
     var buttons: Array<Button> = emptyArray()
     var imageViews: Array<ImageView?> = emptyArray()
-    var history: ArrayList<State> = ArrayList()
+    var history: MutableList<State> = ArrayList()
     var step: Int = 0
+    var undo: MenuItem? = null
+    var redo: MenuItem? = null
 
 
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -31,7 +34,6 @@ class MainActivity : AppCompatActivity(), StarterNameDialog.StarterNameDialogLis
         AppCompatDelegate.setCompatVectorFromResourcesEnabled(true);
         setContentView(R.layout.activity_main)
         setSupportActionBar(findViewById(R.id.toolbar))
-
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
             requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE
         }
@@ -41,7 +43,6 @@ class MainActivity : AppCompatActivity(), StarterNameDialog.StarterNameDialogLis
                 Player(names[Side.LEFT.value]),
                 Player(names[Side.RIGHT.value])
         )
-
         textScore = findViewById(R.id.textScore)
         textService = findViewById(R.id.textService)
         buttons = arrayOf(
@@ -52,18 +53,30 @@ class MainActivity : AppCompatActivity(), StarterNameDialog.StarterNameDialogLis
                 findViewById(R.id.imgLeftService),
                 findViewById(R.id.imgRightService)
         )
-
         updateUI()
-
         openStarterNameDialog()
     }
 
     override fun onCreateOptionsMenu(menu: Menu): Boolean {
         menuInflater.inflate(R.menu.main, menu)
+        undo = menu.findItem(R.id.action_undo)
+        redo = menu.findItem(R.id.action_redo)
         return super.onCreateOptionsMenu(menu)
     }
 
     override fun onOptionsItemSelected(item: MenuItem) = when (item.itemId) {
+        R.id.action_undo -> {
+            step--
+            reloadState()
+            redo?.isVisible = true
+            true
+        }
+        R.id.action_redo -> {
+            step++
+            reloadState()
+            undo?.isVisible = true
+            true
+        }
         R.id.action_new_match -> {
             startActivity(
                     Intent(this, MainActivity::class.java).apply {
@@ -81,15 +94,34 @@ class MainActivity : AppCompatActivity(), StarterNameDialog.StarterNameDialogLis
         }
     }
 
-    fun reloadState(): {
-        history[step].apply{
-            players.zip(score).forEach{(player, playerScore) -> player.score = playerScore}
-            serviceSide = service
+    fun saveState() {
+        val state = State(players.map { it.score }, serviceSide)
+        if (step == history.size) {
+            history.add(state)
+        } else {
+            history[step] = state
+            history = history.subList(0, step+1).toMutableList()
+        }
+        if (step > 0) {
+            undo?.isVisible = true
+        }
+    }
+
+    fun reloadState() {
+        history[step].let{
+            players.zip(it.score).forEach{(player, score) -> player.score = score}
+            serviceSide = it.serviceSide
             relaunchSide = when(serviceSide) {
                 Side.LEFT -> Side.RIGHT
                 Side.RIGHT -> Side.LEFT
             }
         }
+        when(step){
+            0 -> undo?.isVisible = false
+            history.size - 1 -> redo?.isVisible = false
+        }
+        this.step = step
+        updateUI()
     }
 
     fun openStarterNameDialog() {
@@ -108,7 +140,7 @@ class MainActivity : AppCompatActivity(), StarterNameDialog.StarterNameDialogLis
             Side.LEFT -> Side.RIGHT
             Side.RIGHT -> Side.LEFT
         }
-
+        saveState()
         updateUI()
         Toast.makeText(applicationContext, R.string.info, Toast.LENGTH_LONG).show()
     }
@@ -142,25 +174,18 @@ class MainActivity : AppCompatActivity(), StarterNameDialog.StarterNameDialogLis
     }
 
     fun updateScore(scoringPlayer: Player) {
-        val state = State(players.map { it.score }, serviceSide)
-        if (step >= history.size) {
-            history.add(state)
-        } else {
-            history.removeAt(step + 1)
-            history[step] = state
-        }
-        step ++
-
         if ( !matchIsFinished() ) {
+            step++
             scoringPlayer.score++
             if (players.sumBy { it.score } % 2 == 0) {
                 serviceSide = relaunchSide.also { relaunchSide = serviceSide }
             }
+            saveState()
+            updateUI()
         }
         if ( matchIsFinished() ) {
             openEndOfMatchDialog()
         }
-        updateUI()
     }
 
     fun matchIsFinished(): Boolean {
diff --git a/app/src/main/java/adrienmalin/pingpoints/StarterNameDialog.kt b/app/src/main/java/adrienmalin/pingpoints/StarterNameDialog.kt
index ed6b802..74b44cc 100644
--- a/app/src/main/java/adrienmalin/pingpoints/StarterNameDialog.kt
+++ b/app/src/main/java/adrienmalin/pingpoints/StarterNameDialog.kt
@@ -47,7 +47,7 @@ class StarterNameDialog : DialogFragment() {
             setView(namesView)
             setPositiveButton(R.string.go_button) { dialog, id ->
                 mainActivity?.setStarterName(
-                        when ((namesView.findViewById(R.id.radioGroup) as RadioGroup).checkedRadioButtonId) {
+                        when (namesView.findViewById<RadioGroup>(R.id.radioGroup)?.checkedRadioButtonId) {
                             R.id.radioLeftPlayer -> Side.LEFT
                             else -> Side.RIGHT
                         },
diff --git a/app/src/main/java/adrienmalin/pingpoints/classes.kt b/app/src/main/java/adrienmalin/pingpoints/classes.kt
index aa62ece..7a54bcf 100644
--- a/app/src/main/java/adrienmalin/pingpoints/classes.kt
+++ b/app/src/main/java/adrienmalin/pingpoints/classes.kt
@@ -19,7 +19,7 @@ enum class Side(val value:Int) {
 
 data class State(
         val score: List<Int>,
-        val service: Side
+        val serviceSide: Side
 )
 
 @SuppressWarnings("deprecation")
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index 4f91c78..7f73749 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -42,8 +42,7 @@
                 android:layout_marginEnd="8dp"
                 android:layout_marginStart="8dp"
                 android:layout_weight="1"
-                android:paddingLeft="16dp"
-                android:paddingRight="16dp"
+                android:gravity="left"
                 android:textAppearance="@style/TextAppearance.AppCompat.Large"
                 app:layout_constraintBottom_toTopOf="@+id/linearLayoutButtons"
                 app:layout_constraintEnd_toEndOf="parent"
@@ -59,8 +58,7 @@
                 android:layout_marginLeft="8dp"
                 android:layout_marginStart="8dp"
                 android:layout_weight="1"
-                android:paddingLeft="16dp"
-                android:paddingRight="16dp"
+                android:gravity="right|center"
                 android:textAppearance="@style/TextAppearance.AppCompat.Large"
                 app:layout_constraintStart_toStartOf="parent"
                 app:layout_constraintTop_toTopOf="parent"
diff --git a/app/src/main/res/layout/starter_name_dialog.xml b/app/src/main/res/layout/starter_name_dialog.xml
index 0372b7d..60b4341 100644
--- a/app/src/main/res/layout/starter_name_dialog.xml
+++ b/app/src/main/res/layout/starter_name_dialog.xml
@@ -19,13 +19,13 @@
             android:id="@+id/radioLeftPlayer"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:layout_weight="1"
+            android:layout_weight="0"
             android:checked="true"
             android:inputType="text" />
 
         <android.support.design.widget.TextInputEditText
             android:id="@+id/inputLeftPlayerName"
-            android:layout_width="100dp"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:layout_weight="1"
             android:hint="@string/name"
@@ -36,12 +36,12 @@
             android:id="@+id/radioRightPlayer"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:layout_weight="1"
+            android:layout_weight="0"
             android:inputType="none" />
 
         <android.support.design.widget.TextInputEditText
             android:id="@+id/inputRightPlayerName"
-            android:layout_width="100dp"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:layout_weight="1"
             android:hint="@string/name"
diff --git a/app/src/main/res/menu/main.xml b/app/src/main/res/menu/main.xml
index d363e76..4999268 100644
--- a/app/src/main/res/menu/main.xml
+++ b/app/src/main/res/menu/main.xml
@@ -1,6 +1,20 @@
 <menu xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:android="http://schemas.android.com/apk/res/android">
 
+    <item
+        android:id="@+id/action_undo"
+        android:icon="@drawable/ic_undo"
+        android:title="@string/undo"
+        app:showAsAction="ifRoom"
+        android:enabled="false" />
+
+    <item
+        android:id="@+id/action_redo"
+        android:icon="@drawable/ic_redo"
+        android:title="@string/redo"
+        app:showAsAction="ifRoom"
+        android:visible="false" />
+
     <item
         android:id="@+id/action_new_match"
         android:icon="@drawable/ic_new_match"
diff --git a/app/src/main/res/values-fr/strings.xml b/app/src/main/res/values-fr/strings.xml
index ca1c692..85c4415 100644
--- a/app/src/main/res/values-fr/strings.xml
+++ b/app/src/main/res/values-fr/strings.xml
@@ -17,8 +17,10 @@
     <string name="share_button">Partager</string>
     <string name="share_subject">Match Ping Points : %s contre %s</string>
     <string name="share_message">%s contre %s:\n%s a gagné par %d à %d\nPing Points est disponible sur Google Play</string>
-    <string name="PingPointsCredits">Ping Points par Adrien Malingrey</string>
+    <string name="PingPointsCredits">Ping Points par Adrien Malin</string>
     <string name="iconCredits"><div>Icônes par <a href="http://www.freepik.com" title="Freepik">Freepik</a> chez <a href="https://www.flaticon.com/" title="Flaticon">www.flaticon.com</a> Licence <a href="http://creativecommons.org/licenses/by/3.0/" title="Creative Commons BY 3.0" target="_blank">CC 3.0 BY</a></div></string>
     <string name="about">À propos</string>
     <string name="service_img_description">Service</string>
+    <string name="undo">Annuler</string>
+    <string name="redo">Rétablir</string>
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index efc70bb..6c03b86 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -18,8 +18,10 @@
     <string name="share_subject">Ping Points Match: %s vs. %s</string>
     <string name="share_message">%s vs. %s:\n%s won by %d to %d\n\nGet Ping Points on Google Play</string>
     <string name="radioText" translatable="false"></string>
-    <string name="PingPointsCredits">Ping Points by Adrien Malingrey</string>
+    <string name="PingPointsCredits">Ping Points by Adrien Malin</string>
     <string name="iconCredits">Icons made by &lt;a href=&quot;http://www.freepik.com&quot; title=&quot;Freepik&quot;&gt;Freepik&lt;/a&gt; from &lt;a href=&quot;https://www.flaticon.com/&quot; title=&quot;Flaticon&quot;&gt;www.flaticon.com&lt;/a&gt; is licensed by &lt;a href=&quot;http://creativecommons.org/licenses/by/3.0/&quot; title=&quot;Creative Commons BY 3.0&quot; target=&quot;_blank&quot;&gt;CC 3.0 BY&lt;/a&gt;</string>
     <string name="about">About</string>
     <string name="service_img_description">Service</string>
+    <string name="undo">Undo</string>
+    <string name="redo">Redo</string>
 </resources>