If you're a fan of retro gaming you'll be happy to hear that a brand new batch of "Sierra Classics" has been released onto the Steam store. Some of them, such as Arcanum - Of Steamworks & Magick Obscura, you might recognize due to their status as a cult classic these days, but there's also some lesser-known games such as Phantasmagoria and Police Quest.
Most of these games have been available for a while on GOG and other marketplaces, but if you feel the need to have all of your games united under Steam's banner, now you have a chance to do so with some of Sierra's old school stuff as well. Here's the full list:
• Gabriel Knight: Sins of the Fathers
• Gabriel Knight 2: The Beast Within
• Gabriel Knight 3: Blood of the Sacred, Blood of the Damned
• Arcanum - Of Steamworks & Magick Obscura
• Quest for Glory Collection
• Phantasmagoria
• Phantasmagoria 2
• Caesar 3
• Caesar 4
While I've enjoyed many of the games on that list, it is Arcanum - of Steamworks & Magick Obscura that I believe to be most worthy of your time. It is an old school RPG quite similar to Baldur's Gate, and while the gameplay itself might not be amazing by today's standards, the story and the world it all takes place in are some of the best you'll encounter. There's plenty of choices to make, interesting characters to talk to, and naturally, a whole bunch of enemies to beat up with either technology or magic.
Also, for those of you that wish to be a bit... adventurous in your RPGs, Arcanum allows you to roleplay as a blithering idiot, with all of the hilarity that comes with you trying to save the universe while being unable to tie your own shoes! I wouldn't recommend it for your first playthrough due to obvious reasons, but its a nice way of experiencing the world for a second time as it gives you a rather unique perspective on things. Have fun!