Some games are very large. They take a very long time to map, and sometimes they are tricky to map so you can't do it very fast. This inevitably leads to you sometimes giving up halfway through. Here are some of the games that I've worked on a bit but haven't completed yet.
I mapped it several years ago, but only the overworld and I made some mistakes in it (about half the map was misaligned by one pixel). I started remaking it but I didn't finish. Also, the dungeons need to be mapped and I don't want to play through it all again which is needed to get the bosses. Youltar has mapped it anyway, although he's not as pernickety as I am about getting the enemies on the maps.
Notice that one of the screens in the forest is wrong... it's there in the Japanese version but broken in the Export version.
Not a priority for me to complete.
PS fansites have more maps, but maybe mine will be better quality. They might help with my secret disassembly project, too. Just this one done so far...