Unreal Engine BT's changing based on states. Proof of concept

When to use:

When you want to create a lot of small generic BTs and combine them for AI characters
When you want to create AI characters with interaction based logic. Interactions could be used as states
When you want to have same behavior for some states for all AI characters (for example, Disabled/Stunned state)
When you want to try something new :)

Main concept:

AI character has specific controller
Controller has map with different behaviors based on states
Every state has own BT

Test implementation:

Spawn legioner with "Space". State changes to Spawning. BT starts
After BT is end, it's waiting
Press "1" to change state to Attacking. Old BT is stopped and new one is running
BT is working until we press "2" to change state to Blocking. Old BT is stopped and new one is running

How to improve:

Buffer for queue of states to change
Change states conditions implementation