Hi Bim
Animations - creating, editing, …
Advanced A.I - can run, can shoot, can reload…
UE4 AI Tutorial: Shooting at the Player Part 1 - YouTube
C++ programming
http://www.sololearn.com/Course/CPlusPlus/
UMG Animations
Crafting/Inventory In UE4 Bonus Ep1: UMG Animation Basics - Keyframes and Curves - YouTube
Save Game
UE4 Save/Load Tutorial with Structures - YouTube
Mission Select
Wait
Open World - like side quests or mission selection in real
Wait / Above, same thing
Weapons - reload, shoot, +animations, damage
See Animations
DAMAGE: UE4 Tutorial - Health Bar + 2 Ways to Take Damage - YouTube
Stamina, HP, and stuff + UMG
Fall Damage - bigger height, bigger damageThat is easy to work out, you will learn that along the way
Inventory and Crafting
UMG UI Inventory: Project Overview | 01 | v4.8 Tutorial Series | Unreal Engine - YouTube
Switch for example in world with third person to car mode when entering’
*Easy, you will pick that up over *
As you can see, A simple few YouTube searches and you get most of you answer. Just simple search “UE4…”
- UE4 Damage YouTube Search
- https://www.youtube.com/results?search_query=ue4+damage
But this should get you going. IF this is enough, Mark questions resolved 
Regards