Hotel Carone is a Deus Ex Mod/FM (FM=Fan Mission).
It consists of 6 maps; 4 of them playable, 1 End-Sequence and 1 "Main Menu background map".
The Mission is set right after Mission 3 of the original game and assumes you haven't killed Lebedev in the 747, and that's about all the information you really need to play the mod.
http://www.carone1.de/HotelCarone/