Most A.I. in games today is based on a combination of two systems. The first being a waypoint system. These would be key points in the map that the A.I. should be traveling to at some point, for whatever reason.
The second is a hierarchy of importance. The A.I. might have a routine set for exploring, then one set for defending itself, and then another for chasing after the player. The routine chosen would be based on factors like Player health, enemy health, ammo remaining or are they near a power up etc. These different routines are ordered by importance and the best one is chosen based on the situation the A.I. is in.
So, the combination of the two then (for example) might be this: A.I. is wandering from point to point and spots the player. A.I. has full health and ammo so begins a chase. A.I. health drops too low so it looks for a nearby point to run to and get health, etc etc.
Sorry if that was obvious stuff, but all of this can be set up in Construct relatively easily with groups of events, private variables and containers.