Loop Mod is an addition to Black Mesa's On a Rail chapter, adding a couple areas to the very first map of the chapter. The mod reinstates the looped gameplay that was present in the original Half Life but was left out of Black Mesa, in part because the original design was deemed confusing. This issue has (hopefully) been done away with in the mod. It also reinstates three iconic areas from the original as well. The mod also fixes some design errors that were present in the original map. Comes with On a Rail Uncut compatibility.
I am really surprised that the BM Dev Team left this out, It is not confusing, it adds more fun to the game especially if you Play this map and OARUncut. Great Mod