I want to play hellfire with a friend but i have no options. In classic is an option but in hellfire not :(

Hellfire was released as single-player only.

As I remember 20 yrs ago I played this multiplayer over a LAN. There wasn't any issues ... until ... we entered the Nest ... the whole screen was so scrambled we were lucky to find the exit and return to the surface. As far as I recall we never tried entering the Crypt, presumeably the same issue would occur. As far as the other 16 levels were concerned we didn't run into any problems other than those typical for running the program between two computers connected by a serial cable, such as monsters visible to one player but not the other.