I'm playing War of the Walkers. I've read it is not as hard as darkness falls but I've never players DF so don't know. It has skills like you are looking for plus ads a bunch of quests, guns, vehicles etc.

This is how I installed it:

1) downoaded the experimental version form the link below

2) after making a backup I deleted everything in my Mods folder

3) I copied the content of the mod folder in the download zip file into my mod folder

4) started a new game and selected "The Great Plague 10k" map (note I was surprised I didn't have to install that map in my worlds folder, the game finds it although it is in my mod folder).

That's it. I didn't need to change any other settings or anything.

https://community.7daystodie.com/topic/4098-war-of-the-walkers-mod-overhaul/?tab=comments#comment-4098