Gamers Above 30, What Older Games Would You Still Recommend to Younger Gamers?

Alright lots of recommendations in here, some that are making me question how old I am now since some of these don't strike me as old enough to require a recommendation but I'll just suggest one as a bit of a dark horse.

Tyrian 2000, the classic PC Shmup of a time long gone. Oh and I guess Jazz Jackrabbit cause that soundtrack is funky.