I heard Ultima IV was the game that changed the face of RPGs. It's available for free when you sign up for GOG.
Frog Fractions may not be a true text based game, but it has text based section. I tried when I heard about it on Giantbomb and it is hilarious. You can find that for free here: Frog Fractions | Twinbeard Studios
Homemade Movies take a well known scene or trailer and convert it to a homemade look. Check out how their work compares to the original and some behind the scenes of how they do it all.