I created a AI movement engine for firefly. Currently it has a random movement engine and an engine that follows the player. As i get more worked out i.e. changing floors and switching form roam to chasing, I'll add them (but more than likely they will be examples since every game is different). The grid is set up where you can change it without searching through the code using a global value but you will need to resize the AI, path end and walls to match. Here's a video as well as a link to where you can get the example from on my website.