i recently heard and saw something that zombie and minecraft lovers will love. what i talk about is a minecraft level for l4D which has a lot of dark areas, minecraft physics and ladders and caves that will lead you in circles. it is only available for pc as a custom map, i highly recommend it, but is really scary because of the lighting.
the link for the awsome gameplay is here: http://www.youtube.com/user/CaptainSparklez#p/u/35/nTPkeREeHaQ
the download link is here for the map, i recommend: http://www.l4dmaps.com/details.php?file=7457
have fun, and i really like these vids so post up yur experience with fraps or something to here.
Enjoy