Well, if there are adventure games that are really great for boring afternoons, are Eric the Unready, Shannara, Death Gate, Legend of Kyrandia 2, Callahan's Crosstime Saloon, Discworld, you can download these from our site, and all of the LucasArts adventure games (Loom, Day of the Tentacle, Sam & Max: Hit the Road, Full Throttle, Monkey Island series, Grim Fandango). However all of those have to be paid for. They are available on Steam for a few bucks each.
Other than that, you might want to try some RPGs as well, I recommend Ultima VII, Eye of the Beholder, Wizardry VI, Darklands, and Betrayal at Krondor.
One more thing, if you can get Gobliiins, Gobliins 2, or Goblins 3, consider yourself lucky and play them until they're completed.
