I executed black ops 3 by using Cheat Engine.
And entered offline multiplayer mode.

and here is my c# source code. but It doesn't work. I don't know why..
please help..

Code:
        #region API
        [DllImport("kernel32.dll", EntryPoint = "OpenProcess")]
        public static extern IntPtr OpenProcess(
            uint dwDesiredAccess,
            bool bInheritHandle,
            int dwProcessId);

        [DllImport("kernel32.dll", EntryPoint = "ReadProcessMemory")]
        private static extern bool ReadProcessMemory(
            IntPtr hProcess, IntPtr lpBaseAddress,
            [Out] byte[] lpBuffer,
            int dwSize, 
            [Out] int lpNumberOfBytesRead);

        [DllImport("kernel32.dll", EntryPoint = "WriteProcessMemory")]
        private static extern bool WriteProcessMemory(
            IntPtr hProcess, 
            IntPtr lpBaseAddress, 
            byte[] lpBuffer, 
            uint nSize, 
            [Out] int lpNumberOfBytesWritten);
        #endregion

        private static int ProcessID = -1;
        private static IntPtr ProcessHandle = IntPtr.Zero;

        private bool Connect()
        {
            Process.EnterDebugMode(); // gain debug privileges

            Process[] processes = Process.GetProcessesByName("BlackOps3");
            ProcessID = processes[0].Id;

            if (ProcessID == 0)
            {
                Process.LeaveDebugMode();
                return false;
            }
            ProcessHandle = OpenProcess(0x001F0FFF/*PROCESS_ALL_ACCESS*/, false, ProcessID);

            return true;
        }
        private void Disconnect()
        {
            Process.LeaveDebugMode(); 
        }

        private uint bullets = 0x001F0FFF; // bullet

        private void 적용_Click(object sender, RoutedEventArgs e)
        {
            if (Connect() == false) { return; }

            WriteProcessMemory(ProcessHandle, (IntPtr)bullets, BitConverter.GetBytes(99), 4/*an int is 4 bytes in size*/, 0);
            Disconnect();
            //MessageBox.Show("haha");
        }