Arx Fatalis

I think taking the magic route is the most fun. It's difficult at startup and you have to deal with the terrible UI for memorizing and casting spells but by early teens you'll be hovering, running really fast, throwing fireballs, slowing down time, summoning demons (or demonic chickens), and raising the dead. The best armor in the game can be found pretty early and it has really low strength requirements so I was a spell casting, heavy armored, sword wielding badass by the end.

This is important so listen up. In one of the early dungeons you'll find something called an Akba stone or something to that affect. If you pick it up (and I recommend not doing so) DO NOT DROP IT!!! It's required to reach the final boss and it's otherwise a seemingly useless item that takes up a big chunk of inventory. If you discard it, you'll have to find it.

Which brings me to my second point; there's a cavern early on with a shining forcefield and a dude patrolling within the forcefield (you'll know you're in the right area because a quest here involves rescuing someone from cultists). DO NOT DROP THE FORCEFIELD UNTIL YOU'RE READY TO DO SO!!! Inside is the final dungeon but more importantly there are two enemies patrolling here; a priest and a super fast guard. You'll likely miss the priest because he'll run away BUT HE HAS THE FINAL AKBA STONE. If you miss him, you'll have to hunt him down throughout the entire game world because NPCs can run between levels.

This might sound like an annoyance but I fucked myself out of the last boss because of it. Arx Fatalis is otherwise an awesome, atmospheric game that really feels like a worthy successor to Ultima Underworld. Enjoy it.