Mouse Movement doesn't work in a Game

Question

void MausBewegung(object sender, EventArgs e)
{
    Cursor.Position = new Point(Cursor.Position.X + 10, Cursor.Position.Y + 10);
}
void MausBewegungZurück(object sender, EventArgs e)
{
    Cursor.Position = new Point(Cursor.Position.X - 10, Cursor.Position.Y - 10);
} 

So I'm using this, everywhere the mouse moves, but in a game it just does nothing. Already tried to run as administrator, still doesn't help.

private void button3_Click(object sender, EventArgs e)
    {    
    InitializeComponent();
    System.Windows.Forms.Timer ShakerZwei = new System.Windows.Forms.Timer();
    System.Windows.Forms.Timer SechsSekunden = new System.Windows.Forms.Timer();
    ShakerZwei.Interval = 6800;
    SechsSekunden.Interval = 6000;
    SechsSekunden.Tick += new EventHandler(MausBewegung);
    ShakerZwei.Tick += new EventHandler(MausBewegungZurück);
    SechsSekunden.Start();
    ShakerZwei.Start();
}
void MausBewegung(object sender, EventArgs e)
{
    Cursor.Position = new Point(Cursor.Position.X + 10, Cursor.Position.Y + 10);
}
void MausBewegungZurück(object sender, EventArgs e)
{
    Cursor.Position = new Point(Cursor.Position.X - 10, Cursor.Position.Y - 10);
}