I would expect more like 25% completing the game, especially for how hard it gets in the middle. Also with youtube guide videos, there is little to prevent a person from completing a game. Growing up in the 90's you had to have a subscription to a game player magazine to get affordable guides on beating a game. Now those magazines just talk about upcoming games and reviews... no more multi-page lay out of side scrolling dungeons.

Every time there I run into trouble on the road, there is always a dwarf at the bottom of it. Don't they know how to drive above ground?