Just a couple of suggestions, I've been reading HP Lovecraft lately and I think it could be fun to incorporate some monsters from his writings, maybe horrific creatures spawned from darkness, mysterious sounds at night when you try to sleep, that follow you like a curse, maybe even randomly generated 'deep one' villages, with hidden underground full of mysterious artifacts and danger.
I'm not sure if you are familiar with his works, or you think it'd fit with the feel of the game, but it's just something I thought about this morning as I was making breakfast.
Edit:
Also, I get the following error when I try to make the latest from the repository:
g++ -o cataclysm -g obj/bionics.o obj/bodypart.o obj/color.o obj/computer.o obj/crafting.o obj/event.o obj/faction.o obj/field.o obj/game.o obj/help.o obj/item.o obj/itypedef.o obj/iuse.o obj/keypress.o obj/line.o obj/main.o obj/map.o obj/mapgen.o obj/mapitemsdef.o obj/mission.o obj/missiondef.o obj/mission_end.o obj/mission_place.o obj/mission_start.o obj/monattack.o obj/mondeath.o obj/mongroupdef.o obj/monitemsdef.o obj/monmove.o obj/monster.o obj/mtypedef.o obj/newcharacter.o obj/npc.o obj/npcmove.o obj/npctalk.o obj/output.o obj/overmap.o obj/player.o obj/ranged.o obj/rng.o obj/settlement.o obj/setvector.o obj/skill.o obj/texthash.o obj/trapdef.o obj/trapfunc.o obj/weather.o obj/wish.o -lncurses
obj/game.o: In function `game':
/home/jake/Cata/Cataclysm/game.cpp:151: undefined reference to `map::map(std::vector<itype*, std::allocator<itype*> >*, std::vector<itype_id, std::allocator<itype_id> > (*) [82], std::vector<trap*, std::allocator<trap*> >*)'
/home/jake/Cata/Cataclysm/game.cpp:151: undefined reference to `map::map(std::vector<itype*, std::allocator<itype*> >*, std::vector<itype_id, std::allocator<itype_id> > (*) [82], std::vector<trap*, std::allocator<trap*> >*)'
obj/game.o: In function `game::nuke(int, int)':
/home/jake/Cata/Cataclysm/game.cpp:5186: undefined reference to `map::map(std::vector<itype*, std::allocator<itype*> >*, std::vector<itype_id, std::allocator<itype_id> > (*) [82], std::vector<trap*, std::allocator<trap*> >*)'
collect2: ld returned 1 exit status
make: *** [cataclysm] Error 1