Don't forget to make a lot of savegames.
In Act 2 and Act 3 a special quest is the last one and you don't know it.
When you are in these special quests you can't go back and you can't finish the other quests.
You can also lose important items even your pyramids if you don't take care to have them in your inventory when you begin the last main quest.
Be careful too with your items in the battlefields and in "the necromancer's quests"
Barta