Pokemon Nature is a hack of Pokemon FireRed.
Pokemon Ukemerald is a hack of Pokemon Emerald.
Pokemon Complex Crystal is a hack of Pokemon Crystal, the first version of Generation II. Actually, there was a hack named Complex Crystal before, but it wasn’t finished.
Pokemon Iron Version is a hack of Pokemon Emerald. Actually there are two versions: Pokemon Iron and Pokemon Steel, but they are not so different from each other.
Pokemon Sea Green Advance is a hack of Pokemon LeafGreen. It is not another boring hack like some others, according to the words of this author.