Hexen2
FTE supports Hexen2, singleplayer
YOU MUST INSTALL THE HEXEN 2 PATCH: VERSION 1.11
Any other version is not unsupported by FTE.
The patch is available at many places, but I would advise you get from this location: [Official Raven Games site] This ensures you don't pick up a virus.
Usually you would copy all the Hexen 2 pak files from /hexen/data1/ into the /quake/fte/ folder. But there is a trick to avoid this.
I load have a batch file called "FTE (Hexen2).bat", which avoids copying all pak files from the quake3 folder, which contains the following:
fteglqw.exe -basedir c:\games\quake -basegame id1 -basegame qw -basegame ..\hexen2\data1 -basegame fte +exec noodlesqw +exec noodlesfte +exec noodlesirc
Above assumes that Quake is installed in c:\games\quake\ and Hexen 2 is installed in c:\games\hexen2\