I would quite happily put this series down as my favourite game series of all time ever, ever, EVAH! (Whuts Doom3? Never heard of it... nope... never).
It started with Wolfenstein 3D. Me Dad brought it home, and we lost our selves in a nazi castle, fighting hoards of... well... nazis... and zombies.
Then he bought DOOM home... and omg... it was that good... even my Mum started playing it! :O (I still imagine she pictured it was the rest of the family she was taking the chainsaw to).
Level design was great, the monsters were iconic (CYBERDEMON), sound effects were incredible (so much so that some have been used in movies for the last few decades, from certain doors opening, to the certain scream of a monster you destroy (I could be wrong here, and these sounds were around before DOOM?)).
But even the way the difficulty ramped up... I enjoyed. Mobs weren't harder, or did more damage... there was just a shed load more of them!
And you know what? I don't regret getting them on the consoles either, because DOOMII on the XBox had a whole new campaign released just recently, and is a really good well designed campaign!
I want more classic DOOM! MORE I TELL THEE!