Over 22,222 downloads within ten years of release! DXN - Deus Ex: Nihilum is a First Person Shooter mod set in an alternate Deus Ex continuity. It features made-from-scratch original content while also extensively featuring material from the UNATCO Born mod (used with permission from fender2k1, UB's project leader) and Deus Ex: Revision (2011 build - used in accordance with the mod's license).
Just replayed the mod and had even more fun than on the first play.
The maps are rich in details, the storyline is interesting. The voice acting isn't that great, but it is compensated by occasional joke lines in the dialogues.
Anyway, missing this one would be a mistake.