I think the skill tree if expanded should go to different specializations that would make it more reasonable for people to not shot each other on sight.
It would need few additional items, animations etc. and then between clans and groups could be fractions, also i think it would be good to have maximum 2 specializations per character. Rest of the experience could be stacked on the last skill that would change by 0,00001% or whatever.
If You are already dying from radiation it would be nice if a doctor around would see Your flare right?
On the way to Your goal could be also consequences for example if You choose the Policeman path You have to smoke cigarettes / drink alcohol
So mostly we need the professions that will be main goals for the character and the side path as a hobby or something like that.
Oh and one last thing, a random package as a loot dedicated for Your profession so that everybody will get a different result.
As for professions
3 steps per skill - 1st step enables the choice
1 Use of pain killers on others with better results then antibiotics then vaccine (3 steps)
( Phonophobia [loses accuracy when hearing gunshots or explosions] OR Haemophobia [slower use of rare meds] )
2 Is able to detect wounded players from a further distance (3 steps)
( Chunky [slower movement, faster use of stamina] OR Fragile [more vulnerable to blood loss, breaks]
3 Antivirus, (3 steps 25% 50% 75%) and then 75+ till 90%
Police officer -
1 Better accuracy with pistols, SMG's, shotguns
( Clumsy [making more noise] OR Glutton [needs more food]
2 Can craft baton, handcuffs, taser
( Smoked cigarettes [faster lose of stamina] OR depression [slower regeneration of stamina, faster lose of health when infected]
3 Faster reload of pistols, SMG's, shotguns (3 steps then +~)
1 Better accuracy with pistols, rifles, special weapons
( Determined [runs faster but loses more stamina] OR Patient [runs slower but uses less stamina]
2 Can craft military shiv, makeshift grenade, makeshift mine
( Blinded [see less at night] OR PTSD [randomly shots a weapon]
3 Less vulnerable to pain (3 steps then +~)
1 Needs less resources to craft
( Scotophobia [loses accuracy at night] OR Heliophobia [loses accuracy during day]
2 Can craft gas-mask, flamethrower, night-vision
( Allergic [needs more meds] OR Aichmophobia [does less damage with sharp weapons]
3 Can held more items in backpacks and is crafting faster.
1 Needs less water, food, meds (3 steps)
(Anthropophobia [loses accuracy when teaming with others] OR Ex-alcoholic [loses more stamina]
2 Can craft trip wires, bow and arrows, crossbow and bolts
( Hoplophobia [does less damage with guns] OR Fetid [faster attracts zombies]
3 Runs faster and can see better in dark
1 Can craft wrench, repair kit, car keys
( Injured [moves slightly slower] OR Kinemortophobia [Panics when around zombies]
2 Can fix car wrecks
( Algophobia [Panics when not at at least 90% of health] OR Sedatephobia [loses accuracy when it's quiet around]
3 Car's need less fuel and take less damage when mechanic is driving
And as for Hobbies I think there should be maximum 4 to be chosen
Volunteer - Can heal others slightly faster
Modeler - Has slightly better accuracy
ASG - Can reload slightly faster
Chef - Can craft food, some meds slightly faster
Sportsman - Uses slightly less stamina
Acrobatic - Runs slightly faster
Electronic - Crafts slightly faster
Gunsmith - Crafts weapons slightly faster
Archery - Better accuracy and damage from bows
Baseball - Better accuracy and damage from bats and blunt weapons
Camping - Slightly less food consumption
Parkour - Jumps slightly higher
Martial Arts - Increased damage barehanded and with knuckles
Swimming - Increased speed of swimming and breath holding
Skydiving - Take less damage from falling
Ghost hunting - Less Panic
Driving - Better driving skills and less car damage taken
Card collecting - Better loot from loot packages
And so on...
Is this idea possible? Can we take the survival to the RPG level ?