Thanks for the welcome gogoblender
Yes, Titan Quest is alot like Sacred in many ways, but there are two big differences. The first difference is that Titan Quest is more linear than Sacred, while still offering plenty of side quests and places to explore. The second difference is that you do not pick a character at the start of the game, you get to choose 2 "masteries" as you gain levels. If you have the expansion installed there are 9 masteries to choose from: Storm, Earth, Warfare, Spirit, Defense, Nature, Hunting, Rogue and Dream. Combining different masteries will give you various classes e.g.
Storm+Earth = Elementalist
Warfare+Rogue = Assassin
Defense+Storm = Paladin