RPG fans that go way back will appreciate this: Ultima IV: Quest of the Avatar has been released as freeware online, meaning you can download free and play immediately if you so please.
Word has it creator Richard Garriott aka Lord British fought for this one as it is his favourite entry in the series, and finally succeeded. Ultima IV is regarded as the first truly deep installment in the series, offering up complex puzzles and dialogue, more detailed environments, and a virtue system.
Keeping in mind it was released in 1985, here's some gameplay from the Commodore 64 version:
You can download the game at the source -- just be warned it's tough to set up if you've forgotten your circa 1985 install skills. Some may wish to wait for a proper GOG.com release and/or use DOSBox.