Program.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace TestMemory
{
    class Program
    {

        [DllImport("kernel32.dll")]
        public static extern Int32 ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress,
        [In, Out] byte[] buffer, UInt32 size, out IntPtr lpNumberOfBytesRead);

        static void Main(string[] args)
        {

            Process tibia = Process.GetProcessesByName("Tibia")[0];
            ProcessModule module = tibia.MainModule;
            IntPtr handle = tibia.Handle;

            //base address
            UInt32 baseAdr = Convert.ToUInt32(module.BaseAddress.ToInt32());
            Console.WriteLine("Base address            : " + baseAdr.ToString("X"));

            //experience addres -> working!
            UInt32 xpAddr = 0x534660;
            Console.WriteLine("Experience (working)    : " + Convert.ToString(ReadInt32(handle, xpAddr + baseAdr)));

            //gui pointer from MemoryScanner of 
            UInt32 guiPointer = 0x534970;
            Console.WriteLine("Gui pointer address     : " + guiPointer.ToString("X"));

            //game window container
            UInt32 gWindowContainer = guiPointer + 0x30;
            
            //game window width 0x38 -> not working
            UInt32 gWindowWidth = gWindowContainer + 0x38;
            Console.WriteLine("Game width (not working): " + Convert.ToString(ReadInt32(handle, gWindowWidth + baseAdr)));

            Console.ReadLine();

        }

        public static byte[] ReadBytes(IntPtr Handle, Int64 Address, uint BytesToRead)
        {
            IntPtr ptrBytesRead;
            byte[] buffer = new byte[BytesToRead];
            ReadProcessMemory(Handle, new IntPtr(Address), buffer, BytesToRead, out ptrBytesRead);
            return buffer;
        }
        public static int ReadInt32(IntPtr Handle, long Address)
        {
            return BitConverter.ToInt32(ReadBytes(Handle, Address, 4), 0);
        }

    }

}