diff --git a/.vscode/tasks.json b/.vscode/tasks.json
new file mode 100644
index 0000000..15bd63e
--- /dev/null
+++ b/.vscode/tasks.json
@@ -0,0 +1,28 @@
+{
+    "tasks": [
+        {
+            "type": "cppbuild",
+            "label": "C/C++: gcc.exe build active file",
+            "command": "C:\\ProgramData\\mingw64\\mingw64\\bin\\gcc.exe",
+            "args": [
+                "-fdiagnostics-color=always",
+                "-g",
+                "${file}",
+                "-o",
+                "${fileDirname}\\${fileBasenameNoExtension}.exe"
+            ],
+            "options": {
+                "cwd": "${fileDirname}"
+            },
+            "problemMatcher": [
+                "$gcc"
+            ],
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
+            "detail": "Task generated by Debugger."
+        }
+    ],
+    "version": "2.0.0"
+}
\ No newline at end of file
diff --git a/doble_initial.exe b/doble_initial.exe
new file mode 100644
index 0000000..5d14d7f
Binary files /dev/null and b/doble_initial.exe differ
diff --git a/highscores.txt b/highscores.txt
index 4edd5a7..204bdab 100644
--- a/highscores.txt
+++ b/highscores.txt
@@ -1 +1,2 @@
+player_name;4980
 player1;3999
diff --git a/stack.c b/stack.c
index e3a90d4..8e7076e 100644
--- a/stack.c
+++ b/stack.c
@@ -10,24 +10,71 @@
 // Pushes data as pointer onto the stack.
 StackNode *push(StackNode *stack, void *data)
 {
+    StackNode *newNode = (StackNode *)malloc(sizeof(StackNode));
+    
+    if(newNode == NULL)
+    {
+        perror("Fehler! Der Speicher für den neuen StackNode konnte nicht allokiert werden!\n");
+        return stack;
+    }
+    
+    newNode->data = data;   //saves data in newNode
+    newNode->next = stack;  //pushes the newNode on top of stack (newNode->next points to previous Top-Node)
 
+    return newNode;
 }
 
 // Deletes the top element of the stack (latest added element) and releases its memory. (Pointer to data has to be
 // freed by caller.)
 StackNode *pop(StackNode *stack)
 {
+    if (stack == NULL)
+    {
+        perror("Fehler! Stack darf zum poppen nicht leer sein!\n");
+        return stack;
+    }
+    
+    StackNode *old = stack;  //temporary pointer to old top of stack
 
+    stack= stack->next;  //update stack pointer to point to next element
+
+    free(old);  //free the memory of the old StackNode (old->data is not beeing freed)
+    
+    return stack;
 }
 
 // Returns the data of the top element.
 void *top(StackNode *stack)
 {
+    if (stack == NULL)
+    {
+        perror("Fehler! Kann von einem leeren Stack nicht das oberste Element lesen!\n");
+        return NULL;
+    }
+    void *data = stack->data;
 
+    return data;
 }
 
 // Clears stack and releases all memory.
 void clearStack(StackNode *stack)
 {
+    StackNode *current = stack;
+    StackNode *next;
 
+    while (current != NULL)
+    {
+        next = current->next;
+
+        if (current->data != NULL) 
+        {
+            free(current->data);
+            current->data = NULL;
+        }
+
+        free(current);
+        current = NULL;
+        
+        current = next;
+    }
 }
\ No newline at end of file
diff --git a/stack.h b/stack.h
index f7d542d..79f2562 100644
--- a/stack.h
+++ b/stack.h
@@ -8,6 +8,12 @@ The latest element is taken from the stack. */
 #include <stdlib.h>
 
 //TODO: passenden Datentyp als struct anlegen
+typedef struct StackNode
+{
+    void *data;
+    struct StackNode *next;
+} StackNode;
+
 
 // Pushes data as pointer onto the stack.
 StackNode *push(StackNode *stack, void *data);
diff --git a/test_stack.c b/test_stack.c
new file mode 100644
index 0000000..b0579e9
--- /dev/null
+++ b/test_stack.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "stack.h"
+
+void test_on_empty_stack(void)
+{
+    StackNode *stack = malloc(sizeof(StackNode));
+
+    StackNode *a = pop(stack);
+
+    printf("%s", stack);
+}
+
+void test_push(void)
+{
+    int *test_value = malloc(sizeof(int));
+    test_value = (int*)1;
+    StackNode *stack = malloc(sizeof(StackNode));
+
+    StackNode *new_stack = push(stack, test_value);
+
+    
+}
+
+int main()
+{
+    printf("============================\nStack Tests\n============================\n");
+
+    test_on_empty_stack;
+
+    return EXIT_SUCCESS;
+}
\ No newline at end of file