When it comes to games, I often find that architecture can yield the best inspirations – especially when it comes from sources like the BLDGBLOG.
In this case, it's all about trapdoors. Funny things, trapdoors. Even funnier that they are not in much use when it comes to games.
Most levels are, when analysed thoroughly, mostly 2D: they might go up and down and wind around themselves a bit – but in the end, they're just long strips. Trapdoors undermine this simple structure, by opening up unexpected shortcuts. Yes, this might confuse the players … but couldn't this be fun, too?
I have not yet played Deus Ex: Human Revolution, but I do hope that this game uses trapdoors (and other unexpected shortcuts) more often.
A Spatial History of Trapdoors, as BLDGBLOG proposes, would be a good start to explore those devices:
Someone should write a short history of the trapdoor as spatial plot device in Broadway plays, literary fiction, Hollywood thrillers, and even dreams, CIA plots, Dungeons & Dragons modules, and more. How does the trapdoor, as an unexpected space of strategic perforation and architectural connection, serve both to move a plot forward and to give spatial form to characterization?