Zeeaire: This is a good question.
I also loved the soundtrack of Arcanum a lot, more, it's still my favorite soundtrack and it always will be.
It evokes emotions no other piece of music could create, sentimental, nostalgic, pure, directly touching ones heart.
But it's difficult to find anything nearly so excellent.
Even though there are still nice contributions here in this thread I just wanted to add something which slightly reminded me of the soundtrack:
https://www.youtube.com/watch?v=WB4r_hl5BJ4 ...at least the beginning...
and
https://www.youtube.com/watch?v=0zo8sCRCpRY ...but this is with vocals, only the background music resembled it a bit.
Maybe with time one will come across more resembling tunes.
Have you ever heard the music of Sakamoto or Nyman? Here are some links, Contemporary but beautiful.
Both Nyman and Sakomoto are excellent composers. Czech them out if you have time! also one cant forget Arvo Part