Hack Halo 2 with a hex editor.
Although there are some great programs to help you hack Halo 2, you'll occasionally need to get down to the lowest level possible. Welcome to the true old-school method: hexadecimal editing.
This hack shows you one of the most popular (at the time of writing) uses of hexadecimal Halo 2 hacking. That is, adding a new map to the multiplayer maps menu.
Remember that if you mess something up, you can get the original files from your official Halo 2 DVD. First, open the map in a hex editor. In this example, I am using Hex Workshop.
At offset 0x000001BC, you will see the name of the original map in plain text. Change this text to your map name. You must remember that you cannot alter the size of the file. In other words, you have to put in exactly the same number of characters as you remove. If your path is shorter than the original path, then you must replace the missing characters with zeros. You cannot use a string that is longer than the original. In this example, you are changingscenarios\multi\lockout\lockout to scenarios\multi\test\test000000 (see Figures 6-19 and 6-20).
When you type in your new name, you will be typing over the original characters. There is no need to use the Delete key.
Figure 6-19. The original hex before the change
Figure 6-20. The ASCII after the change
Next, open mainmenu.map in one of the Halo 2 modding ...