How To Manually Patch Your ROM Using .xdelta Files

A lot of people have asked me, ‘Isn’t rom hacking illegal?’ Short answer — no. Long answer… if you distribute a pre-patched ROM with your mod installed then you’re also distributing a copyrighted game. This is where things get sketchy. To avoid allegations of distributing a copyrighted game to people who don’t already own that game, modders turn their original work into patches that ROM owners can inject into a copy of their original game.

I’m going to assume that anyone reading this article came here to learn how to patch a romhack they just downloaded so lets jump right in!


First off, Windows users will need to download xdeltaUI and extract it using a program like WinRAR or PeaZip. If you aren’t familiar with extracting files using these programs, I recommend you follow this tutorial.

If you’re a Mac users, download and extract MultiPatch instead. I’ll be using xdeltaUI for this tutorial but MultiPatch will function basically identically aside from a few wording differences.


Second, launch xdeltaUI.exe and a small window with three different file browsers should pop up. Start by pressing the first [Open…] button next to Patch. An explorer window should appear, asking you to locate the .xdelta patch file of the mod you just downloaded. For this tutorial, I’ll be using the Banjo-Kazooie – Smash Bros. Temple mod which I already have downloaded. Once you find this file, double click on it to load the file into xdeltaUI.

Clean ROM…

Next, click the second [Open…] button near Source File. Browse to your clean, unmodified Banjo-Kazooie rom. Two things to be mindful of here:

  1. Make sure the rom you’ve selected is in .z64 format. This is the most common file type for Nintendo 64 roms but a few variations exist that aren’t compatible with xdeltaUI or many other rom hacking tools.
  2. Check any documentation written by the modder whose patch your downloading to find out which region or version your rom must be. Most rom hacks require the v1.0 North American build of a game but it’s always a good idea to double check.

Smash Bros. Temple mod requires just a standard, North American rom so I’ve navigated my browser to ‘Banjo-Kazooie (U).z64’.

Patched ROM…

Finally, click the [ … ] button next to Output File. Here, we simply navigate to a location that we wish to store our romhack. I’ve got a folder specifically for Banjo-Kazooie romhacks as I find keeping mods in my vanilla folder leads to excessive crowding and difficulty navigating to the desired vanilla rom on certain occasions.

Once we’ve picked a destination, name our romhack something unique and be sure to type the extension ‘.z64’ at the end of the file.


At the end of all that, we should be able to click [Patch] and a window should pop up telling us that our new file was patched successfully! Congratulations, you’re ready to play! If you’d like, tweet at @SheeshFr and let me know what romhack you’re playing! 😀

If, however, you didn’t get a success screen at the end, I’ve got an FAQ for you below that will hopefully help you resolve any problems.



Q: I downloaded my patch but it says .zip/.rar at the end, not .xdelta. How comes?

A: You need to extract the contents of this file. Above, I mentioned using WinRAR or PeaZip. Do this then come back if there was a .xdelta patch file. If there’s a .bps file instead, read my other tutorial for that process.

Q: I downloaded a romhack but it’s already in .z64 format. Do I need to patch it?

A: No, you downloaded a pre-patched rom. You should be able to boot it up like normal.

Q: My rom isn’t a .z64 file. If I rename it to .z64, will this process still work?

A: No, a .z64 file is written differently than an .n64 or .v64 file. If you simply rename the extension, you’re going to get an error when patching and it won’t boot properly either.

Q: I got a File Patched Successfully message and I see it in my folder, but when I navigate to it in my emulator, the file isn’t there. What’s up with this?

A: Sounds like you did everything right but left off the ‘.z64’ extension when naming the output file. Rename the file in your browser and see if it appears in your emulator.

Q: I did everything right but when I boot up the file in my emulator, I get an error. What gives?

A: There’s a very good chance the romhack requires 8MB of RAM to be toggled in your emulator. Go into your emulator’s settings and try changing the default memory size to 8MB. If your emulator doesn’t have this menu, boot up the game again (despite a crash), navigate to Rom Settings and change Memory Size to 8MB. You might need to reload your emulator after changing property.

Q: Where can I find roms?

A: DuckDuckGo is a truly private search engine. Ask them, they might know better than I would.

Or you know what, call up a local used game shop and ask if they’ll loan you just the license over the phone. Be sure to specify that you want ‘just the license.’ The owner of the store is probably hording like 280 physical copies of what ever game you want to play despite how many they have on the shelf. You don’t want those, you want ‘just the license.’ Is there a finite number of those?

Oh boy, rom hacks lol

Follow me on Twitter, @SheeshFr