I really wish those Thief 1 and 2 games would be re-released based on the Thief 3 engine. The light and shadow effects and the really good textures take their toll on the machine's hardware but just think of "Down in the Bonehoard" (3rd mission of Thief 1) with all that graphics galore of Thief 3.
Overall I liked Thief 3 (aka. Deadly Shadows) very much. More of the good old sneaking around, banging a club on opponents' heads from behind and using all that nice little gadgetry that makes a thief's life so much easier when striking from the shadows (water-, moss-, fire-, gas- and broadhead-arrows, gas- and normal mines and -last not least- climbing gloves). There are even levels where flash bombs become REALLY useful for a change.
But there are also some let-downs, especially compared to Thief 1 and 2. The most irritating one is the way the game just reactivated guards and other inhabitants of the town. You clear your path in true thief style just to find the guards on patrol again a few minutes later. Very irritating but well, it keeps the difficulty level up somehow. Also I do not think that the levels are really big. I remember the levels of Thief 1 and 2 being positively vast at times, so vast that I got lost several times in an attempt to find a path to the next section of a level. This feeling of space is something I hardly ever had while playing Thief 3, the only exception being the excellent Shalebridge Cradle level. This level is also by far the creepiest and most difficult level in Thief 3. The cradle experience alone makes Thief 3 a must-play not only for fans of the Thief series. Sadly, all levels save Shalebridge Cradle are in my humble opinion as a Thief veteran just too easy. The annoying exception to this impression are the loot requirements when playing at expert level. You always need 3 out of 3 so-called "special loot items". What a joy it is to have stolen 98% of all loot and still missing one single (damn) special loot item to finally leave the level... Happy searching!
But I also think that the lower level of difficulty will appeal to new Thief players. And after all there is so much eye-candy plus some decent puzzles to solve that I do not think anyone who plays Thief 3 is going to be bored or disappointed. The game really grows on you but unlike the first two Thief games -if you save resources and keep buying equipment- you will soon find yourself armed to the teeth. At least I had to restrain myself sometimes from just creating a bloodbath with the maximum of all types of arrows and mines at my disposal. So if you like what you see in Thief 3 and you want to try the first Thief games, too, be warned - you will encounter strict limitations of resources there. In fact, I would recommend Thief 3 as an entry to the world of stealthy stealing. The real test for master thieves are Thief 1 (The Dark Project), Thief 2 (The Metal Age) and T2X (Shadows of the Metal Age - a fan project of very high quality, a freely available add-on to Thief 2).
