I have several types of games that I like switching to and forth playing now and then, but there's always one RPG which never really ends (or at least, lasts a really, really long time) and I pour endless time into, and still has a sense of progression. This usually takes the form of ARPGs (used to play the original Sacred and Titan Quest) and I've recently started getting into MMORPGs.
I've been playing Guild Wars 2, presuming that I'd be playing it for a long time to come, until I realised that the endgame is rather shallow and lacks a sense of progression, so I couldn't find much more reason to keep playing it past max level. It leaves me kind of stuck and unable to find another RPG that fits the criteria.
So, Escapists, can you think of a 'long term' RPG?
Edit: I should mention that they should be on PC.