Update

cgi-bin/uebung08/hangman-init.php

@@ -6,7 +6,6 @@ require_once(__DIR__ . "/hangman_lib.php");
     session_start();
     
     initGame();
-    echo "INIT";
-    //header("Location: hangman.php");
+    header("Location: hangman.php");
 
 ?>

cgi-bin/uebung08/hangman_lib.php

@@ -68,7 +68,7 @@ function guessLetter($letter) {
     $newMask = $_SESSION['mask'];
     $wordcontainsletter = false;
     for ($i = 0; $i < count($guessword); $i++) {
-        if ($guessword[$i] === $letter) {
+        if ($guessword[$i] == $letter) {
             $newMask[$i] = $letter;
             $wordcontainsletter = true;
         }