Curse of the Azure Bonds was a major favourite when I was in high school, the second of the AD&D goldbox games. That engine still stands very tall today in fact, with its own newsgroup and sites to download fan made adventures using the "Unlimited Adventures" program. *sigh* Love all of those games very dearly and have played and completed all of them! Might just have to repeat Pools of Darkness one of these days and see if I can finally conquer "Dave's Challenge".
I have to mention Bard's Tale III also, which would probably be my all time favourite RPG period, with its turn based descriptive combat style and classical old school dungeon crawling and riddle solving. Upon discovering this game in 89 or so, I was posessed by the cRPG.
I've got Arcanum to look forward to soon...and I really must get my paws on Temple of Elemental Evil and see if it at least surpasses the horrible abomination that was POR: Ruins of Myth Drannor! Talk about an insult to a classic.
