The most popular choice today are behavior trees. They are very powerful, modular, and there are even visual tools for putting your building blocks together. T

The most popular choice today are behavior trees. They are very powerful, modular, and there are even visual tools for putting your building blocks together. The Unreal engine also comes with such a tool for example: https://docs.unrealengine.com/latest/INT/Engine/AI/BehaviorTrees/QuickStart/ https://docs.unrealengine.com/latest/INT/Engine/AI/BehaviorT... A good intro which highlights flexibility and reuse: http://www.gamasutra.com/blogs/ChrisSimpson/20140717/221339/Behavior_trees_for_AI_How_they_work.php http://www.gamasutra.com/blogs/ChrisSimpson/20140717/221339/... Having said that, FEAR's AI held up really well. It's still top-notch.