Here's a table that shows which engine can be used as a listen server, for the Omicrons. 

Engine	            Omicron	

(GL)Quake	*		
(GL)QuakeWorld			
ezQuake			
FTE			
Fodquake			
DarkPlaces			
QuakeSpasm	*		
Fitzquake Mk V	*		
DirectQ 	 	*	
Engoo			
qbism Super8	*		
ProQuake	 	*	
Qrack	         	*	
