rat_mountain_8

[ihtarlik]

rat_mountain_8 is the only map tile I have been unable to access. I have "played through" several times, trying different things each time. This time, I was going to "completeness," collecting everything unique, visiting every map tile, finish every quest.

According to this site:
https://www.rg-brille.de/etc/AT/AT_checkPlaces.html

The above-named map section is the only place I haven't been. However, based on the Wiki, it doesn't look accessible. It can entered on the west side of the map tile from the ridge above the Aidem Mountain Hideout, but that ridge also seems inaccessible.

I guess I just want to know if it is even accessible in the current version.

[Osho]

It is related to a thief guild quest which involves making a choice and depending on the choice you gain access to this place.
Clearly you made a different choice just like I did and it's now inaccessible in normal game. Not sure if it can be accessed outside quest but, yes, it's accessis linked with a quest. If you search more on the thief guild you will understand the reasons

[Antison]

rat_mountain_8 is the only map tile I have been unable to access. I have "played through" several times, trying different things each time. This time, I was going to "completeness," collecting everything unique, visiting every map tile, finish every quest.

Sorry, but this is impossible. You can not reach every map and receive every item on any given character. Nor can every quest be finished.
If you want to experience the full breath of the game then you need to do it with multiple characters making different decisions every time