No mentions of Super Mario RPG yet? Well under 10 hours, that one.

AD&D Heroes of the Lance NES is apparently trivially short if you map out the maze, but is also apparently one of the worst NES games, so it is probably best not to bother.

Maybe the various episodes of On The Rain-Slick Precipice of Darkness, the Penny Arcade RPG? I've been thinking of going back and finishing those one day.