The "chained in the basement" is a quick cheat to explain why the movie is locked into one location.  I did like how CUBE made it a maze of identical rooms with swapped-out wall panels, kept the look interesting... for a while.  But of course, once they're in one location, how do you keep the horror going?  You torture them.  And yeah, I don't dig torture pron either.  THere's really no point to it, I think (outside of maybe showing off gory effects work).  The only way I can think of to make that interesting or different is to have the main character have to become the killer himself, put the audience in his mind, that would be kind of terrifying, because I think people are always scared of the idea of falling off of that cliff themselves.  And it's also pure tension.

BTW, I just watched "The Sleepover" twice while browsing through Vimeo on my TV.  It's totally the kind of short I want to share with as many people as I can.