Reputation in G3 is paramount, it's what the whole game is about, not to hack and slash your way through the game but to infiltrate each faction to the maximum without confrontation. Once you have gone beyond the faction acceptance limits (primary and/or secondary) you are in a dominant position and can influence situations by diplomacy and respect.
G3 is all about quests and how they are approached.
(a) quest selection - which quests are chosen to complete and the method to achieve 'amicable' solutions.
(b) quest sequence - which quests are done before others.
(c) quest omission - which quests are not accepted, which quests are accepted in journal but not carried out.
I would get to L70 without killing any orcs or human npc's and at the same time getting access into Ishtar. From there the game became extremely hard, i could not find the critical path other than the three branches - orcs, humans, hashishin, and because the game map area is big, replaying is very time consuming. The crucial factor to assist this is in "progressive saved games" - sequencial saving, you would have to make your own written notes as the save system does not allow save game naming. The game is a continuous hurdle, a challenge almost beyond logic...but it's there, to be unravelled by the careful thinking gamer