Here's an overview of how complicated the blueprints in Project Rain are:
|Main character blueprint. I swear I know where everything is. I'm actually organized with all weapons stuff on right side, etc|
|This is a blueprint setup just for a short tutorial level (3-10ish minutes). Made it nice with color depending on the event.|
|Got to love booleans. There's a lot more and they were used almost everywhere.|
It would take too much time to explain anything in detail. Not to mention my approach is nowhere near efficient (I'm an artist). It took several weeks to set up the blueprints with the majority of time figuring out the simplest problems (it's nice to hear I'm not the only developer who struggled with doors). Once you have a system in place, you can reuse old nodes so it would be much easier to add more narrative content after getting things set up.
If you want to learn how to use Blueprints for your Unreal Engine 4 project, check out Youtube channels. The official tutorial videos are a great place to start teaching the theory, then you can search for more complicated stuff like AI in other channels: https://www.youtube.com/watch?v=cRhWc2kAhqI