Loom is a wonderful little game, very sweet story. Played it back on my Amiga.
Never played Nethack, but I played
Larn on the VAX terminal at my dad's job yeeeeears ago.
Outcast is interesting, never played it very far, graphics are somewhat buggy but it does have very nice use of voxel graphics; and damn it was CPU intensive back in the days. Always wanted to play it, but only had a demo and now that I can afford to buy it, well... meh.
Didn't play planescape:torment, but I played Baldurs Gate (or #2, can't remember). Never finished it though, I got massively stressed out at the non-linear gameplay, wanting to explore it all and... argh!
Oh, Clive Barker's Undying ROCKED. Lots of scary moments, nice story, very nice gameplay. I'm tempted to give it a go again sometime, I never finished the last boss

As for classics... Zak McKracken, Maniac Mansion, Day Of The Tentacle. I still think I have my almost-complete walkthrough for Zak lying around somewhere, it ended in the middle of a sentence, as I was writing the walkthrough while playing the game... I forgot that it wasn't 100% done, and then wrapped each and every A4 page in transparent tape. It's back when I.added.dots.between.each.word, because otherwise I couldn't seem to get the spacing just right and stuff was unreadable...