Are there examples of simple enemy AI I can reference?

A project I intend to look into doing in the future is making a coop based Doom 2 style FPS in the Unreal Tournament Universe. Basically a old school Coop fps mod for UT4.

So one of my questions about this is if there are any examples of enemy AI characters that behave like a Doom 2 enemy.

Hand placed by the level designer.
That stays in a sleep state until it hears or sees the player. (It would be cool to have a variation of each enemy that does not react to sound. Deaf Enemies)
Once it sees or hears the player it plays an awake sound
Walks toward the nearest player. Shoots or attempts to melee depending on the kind of enemy it is.

I actually prefer most of the enemies to meander in the same way as the doom bad guys normally do then have more bot like characters who use nodes and A* to track the players last known location. I absolutely LOOOOVE the blueprint system and I plan to live and breath it. I just dont know really how to get started with good variations of enemy AI.

Anyone have any tips?

For c++ there’s the Shooter Game from the Marketplace. It’s really simple and easy to understand the basics.

the best tutorial about ai you can ever find just magnificent from beginning to the end