This isn't a game,it's an experience.
Thief is unlike anything you've ever experienced.Especially if you play on expert,you will never find yourself getting as caught up in a world like you will in Thief.Thief Gold,while not as good as thief 2:The Metal Age,It still stands the test of time.
This is NOT a run and gun.You will die rather quickly if you try that,two strikes from a guard's blade and your dead,and there's easily 45 guards per level.Also,the levels are meant to draw you in,not to be rushed through.You can EASILY spend an hour,maybe even two hours,on most missions,and that's if you don't collect everything.
What tile you walk on,the light in the area,what sound you make,what weapon you have drawn,all affect if the enemy can see you or not.The world sucks you in and when you finally do complete a mission you truly will feel like your a Master Thief,let alone when you beat the game.
The gameworld has tips scattered throughout,during one level I actually found myself drawing a map of guard patrol routes,and then found a journal that told me the secret way in.That's the thing with this game,you really don't play it,you experience it.Sometimes,there really is no way out except to shoot a rope arrow into the rafters and hope for the best.Guards will hear you open a door,take a step,splash in water,and this game is best played with headphones as every single sound counts,and matters.
If you try to play this game like COD,you will die,and you will get frustrated,and not understand how this works.This game takes time,and patience,and a complete understanding of just what will and will not work.Save early,save often,your not here to save the world,your there to save yourself.