Start by creating a new unit moditem, name it as you wish. If you plan to replace a current JA3 unit you need to name it exactly as in the vanilla game, ex. if you want to replace Wolf, you name your unit as "Wolf"


From here you can copy a unit as the original and just tweak the values you want.

Here you can find:

• Group:
  It defines the group this unit belongs, ex: NPCs, Mercs, etc
  
• Id:
  The identification of this unit, not the name, the internal id, ex: "Wolf", "Barry", "Legion_raider"
  
• Comment:
  Just a place to make jokes
  
• Copy from group:
  The group you want to copy from if that's the case
  
• Copy from:
  The unit you want to copy from if that's the case
  
• Object class:
  Black magic, don't touch it

• Is mercenary
  Check this if you want this unit to be recruitable, note that this may cause your unit to be not interactable, just check if you know what you are doing
  
• Full name
  Full name of this unit, leave it if you are creating a general unit
  
• Elite
  Only used for Units with Elite category to get a special name
  
• Elite category
  Same as above
  
• Affiliation
  The "category" this unit belongs, ex: AIM, civilians
  
• Immortal
  nope
  
• ImportantNPC
  check this if you want the indicator over the unit
  
• Reincanate
  nope
  
• Dummy
  never this please
  
• Militia Unit
  Only for militia units
  
• Recurring Villain
  Only for units that will spawn in different stages of the game
  
• Retaliate
  Check this if you want the unit to fight back in case of being attacked, note that it may lead to some weird interactions
  
• Additional Groups
  Use in case you are also mapping
  
• Persistent Session Id
  Last case scenario use as it may lead to some weird stuff, use only if you know what you are doing
  
• Heal Persistent Unit On Spawn
  Same as above

• AI Keywords
  This determines the behaviour of this unit while in AI control, usually "Soldier" is fine
  
• Archetype
  Similar to above
  
• Enemy Role
  Similar to above but also determines where the unit will go when looking for grids, leave it if you are not mapping
  
• Archetype
  well, you guessed, the square hole
  
• Reposition Archetype
  also square hole
  
• Always Use Opening Attack
  square hole
  
• Opening Attack Type
  square hole
  
• PinnedDown Chance
  it goes in the square hole =)
  
• MaxAttacks
  This one determines how many attacks this unit have per turn, different from controlled Units, AI unit can be limited here
  
• Pick CustomArchetype
  black magic, don't touch it

]
For Appearance you need to create an appearance preset before select one here, same goes for voice and equipment.

Attributes are pretty straight forward, use random if you want some flavor.

Save your unit and you are good to go. Have fun GG!