What are patches and assemblers?

A patch contains new code that modifies aspects of the game, and the assembler applies the code to your ROM.

How do I add a patch to my ROM?

Always back up your ROM first. Download Asar and put it in your ROM's folder. Double-click to run it, enter the patch name, then the ROM name.

I get a warning about "xkas" patches in Asar. Should I be worried?

Generally-speaking, no, but Asar has a compatibility flag, ;@xkas - this goes at the top of these files without quotes. This feature is, however, becoming increasingly deprecated.

My ROM crashed when I applied a patch! Why?

This could be down to a number of reasons: using a bad patch, loading a save state after patching, or incompatibility with another patch are some possible reasons. We suggest you seek help in our ASM & Related Topics forum or in #asm over Discord, providing as much information as possible about the patches you have used.

When I apply a patch, another patch I've applied no longer works! Why?

Some patches modify the same code or use the same RAM addresses. You'll need to edit the patches to fix conflicts. Ask in our ASM & Related Topics forum or in #asm over Discord for help.

My patch was working fine, but it suddenly broke - I didn't even apply another patch! What happened?

Lunar Magic silently applies new code as needed when features are activated; it is possible that Lunar Magic overwrote your patch. This is rather rare, however, and many modern patches contain specific safeguards against this kind of conflict.

How do I remove a patch from my ROM?

Download Unpatcher. Alternatively, you can learn how to manually remove patches here.

How do I create my own patches?

There's a tutorial for that here. Note that you should have some ASM knowledge before trying to create your own patches though.