where to start
Countdown
Day of the tentacle sam n max
Wolfenstein
xenon
monkey island i & 2 ( I thought no 3 was also pretty good as well )
populous
zork
Jazz Jackrabbit ( + all the other appoge platformers
, geez just amazing how long did they take to d/l from the bbs and now less than a minute !)
all the usual suspects...
I could carry on for ages as it's really hard to narrow down my fave ones