We've seen some of the ways in which FSMs can be valuable things to add to your projects and how they can make simple AI behaviors much easier, but there are some issues with them.

Traditional FSMs such as the ones we've displayed here can, over time, become unmanageable as you continue to add many different states to them. The difficult part is keeping the number of states to a minimum while also adding complexity by adding new contexts in which your characters can respond.

You'll also have a lot of similar code being written as you'll be rebuilding different behaviors that have pieces of others, which can also be time-consuming. Another thing that's been going on recently in the game industry is AI programmers moving on to more complex ways of handing AI, such as behavior trees.