Hey guys! New Arcanum player here. I still remember the box in stores but sadly my parents would never buy it for me... Perhaps a good thing since it was plagued by bugs but I'm still sad I missed it's grand days.

Anyways, I got to Qintarra and really started liking magic so I am restarting as a mage. My question is what is the max aptitude? I saw something about elves can get 115% (100% plus their racial 15%) but I was wondering if you sell your soul can you get up to 135%?

Thanks!

Well, yes... and no. :)
Your effective aptitude is maxed out at +/-100, but the game keeps track of an excess value if you have it. It can be useful in a couple of ways.
1. As a mage, you can learn some technical skills (Repair and Disarm Traps are of practical use for a mage) or schematics (some crafted items have neutral aptitude, but you can always sell those tech ones - and for a good price!).
2. As a technologist, you can learn some spells that work even with fully tech character (e.g. Temporal school!).
3. There are places in the game world that can shift temporarily your aptitude towards tech (or magick).
In all cases you can still keep your aptitude at maximum, if you have some surplus available.