Setting aside the overt Diablo-Clone label, Titan Quest does what it aims to very well - but just how high does it aim?
Titan Quest is a 2007 PC Action - Role - Playing game, that acts as more of a competently delivered homage to late 90's and early 2000's isometric - perspective hack n' slash games, such as Gas Powered Games' Dungeon siege, Ascaron Entertainment's Sacred and yes, obviously Blizzard's legendary Diablo franchise; while in it's essence it delivers nothing absolutely new on the whole, it does build on some of the more clunky and experimental features of it's indirect predecessors, so with it's distinctly in - depth class based system and "smooth around the edges" dungeon - crawling gameplay, there's more to be found in this CRPG than a mere place - holder for the inevitable next installment in the Diablo series.
Setting the player in the shoes of a stereotypical hero [gender is completely open to the player's personal preference], in the center of a war-torn Greece, ravaged by invasions from both hell and various mythological beasts from the surface alike; and as you might as well have guessed by now, someone wants to destroy this dying world, and you, the yet unknown hero, are the only one in the mood to stop them.
The game spans four to five sections with constantly changing environments and inhabitants [a.k.a. sword bait], yet the pace of everything going on remains relatively similar no matter what the locale - you will hack through hideous sea creatures, half - goat men, centaurs and other creatures of the woodlands, legions of the undead - and yes, a few bosses as well - five of which are, astonishingly enough - evil titans.
Gameplay - wise, everything remains pretty basic - yet well fleshed out; you'll pick a specialty or two throughout the course of the game, upgrade you're skills within these "specialty trees" when leveling up [which can be done by - take a guess; killing monsters - very novel indeed], and gain new specialty attacks and/or spells depending on your class, over the course of the entirety of the game.
Much like most all of the other Action RPG's that it aims at paying sufficient homage to, Titan Quest's gameplay revolves around two major elements - killing and looting. There are a variety of monstrous abominations to be conquered in the vast world of Ancient Greece, a lot of which carry a stunning variety of new weapons and sets of armor which in turn, are used to kill and loot even tougher monsters further through the game. Other than that there's not much to the overall mouse - button spamming gameplay experience, apart choosing how you wish to slay your foes, and of course - with what, which is where the game's uniqueness comes into full-play [pun - intended]; that is to say, the game's skill and leveling systems are entirely non - linear, and how your character progresses, is entirely up to you. So overall, with thousands of possible combinations for different player types, Titan Quest delivers quite some replay value - at least for those who can stand taking on the same monsters with the same rahter primitive combat system all over again.
The single - player of the game lasts about 40 - 80 hours, depending on what side - quests [there are a lot of them, usually having to do with finding some kind of "special loot" or killing some kind of "special foe"] you choose to undertake. Yet, even after [or perhaps before, depending on your gameplay tastes that is] completing the single - player experience, there's a full multi - player component available for up to 8 players to participate in, which is basically the same as the solo - campaign, just with more interaction and the overall fun - factor.
Finally, I can state that while I enjoyed playing Titan - Quest, getting through all the separate chapters, one after the other turned out to be quite laborious after a time, and I found it better to take breaks in between playing all the way through, to avoid driving my base - instincts crazy with the fairly monotonous gameplay.
It's a great omage with everything done right, yet not enough ambition or innovation for that matter.