Looking at the rules it seems that it's not allowed, but most of the version of the game you find now (gog mostly) is running it.

What would it change to allow it?

Should'nt we create a new category allowing grayface patch?

The GOG release does not include Grayface's patch, only Mok's patch, which is why Mok's patch is also allowed on the retail version.

There is no need to allow any other third party modifications.

Good day. It seems that in GoG version when I try to walk north, the party moves a lot slower than when I walk in other directions, it also slightly strafing to the left or right depending on the direction. There was no such thing with Grayface patch. (Same problem in VII and VIII).

It's a known issue but not really something worth allowing the patch in my opinion.

Well, if everyone has this issue, then i'll have to roll with it. Thanks for the quick answer. :)