video game based on The Inferno (which has, incidentally, been called a "tawdry masterpiece," whatever the hell that means), Wired has a list of "10 Literary Classics That Should Be Videogames." While their list includes some sure-to-be-hits like Gulliver's Travels and Heart of Darkness, I personally think The Grapes of Wrath would be boring as hell, educational merit or not.
Island of the Blue Dolphins, by Scott O'Dell
Survive on a deserted island by collecting wood to make a boat and spears, tame a pack of feral dogs, and hunt an octopus.
The Road, by Cormac McCarthy
Fight off cannibals and safely deliver your son to the coast to win. Your reward is death by coughing up a lung.
The True Confessions of Charlotte Doyle, by Avi
Masquerade as a boy on the Seahawk, learn how to climb rigging, stifle a mutiny, prove your innocence when you are charged with murder, and face the final show-down with Captain Jaggery.
The Adventures of Sherlock Holmes, by Sir Arthur Conan Doyle
Solve mysteries with your trusty friend Watson by your side, with a mix of gunfire, martial arts, and blood/guts/gore to perk the game up.
Treasure Island, by Robert Louis Stevenson
Yet another nautical adventure, this time featuring Long John Silver. What can I say? I have a weakness for pirates... yarg.