Getting the last NPC's sprite up and animated happened fairly quickly, especially in comparison to those that preceded it. Of course, that's party due to the fact that this is a flying NPC that will never land. For now, it only has a basic flying/floating animation. I may extend this in the future to include a few more basic actions, but it currently gets the job done. On top of putting together the sprite, all of the unique actions for this NPC type had to be coded in. Truth be told, they are not overly complex, but it was still a decent amount of work to do. The main design element required extending the "checker" object type, as well.
Checker objects operate in a pretty simple manner: check some condition; if it's met, perform an action on some given object in the world. The conditions previously available were the number of NPC's converted, which power-ups have been obtained, etc. One condition missing from this list was proximity of a certain type (or specific) NPC to a given area somewhere on a map. This is functionality that's required for our flying little friend! Currently, the condition checker can only check for this specific type of NPC. It may make sense to extend it further to allow checking on proximity of any type of NPC, but I don't foresee the necessity for that in the near future.
I'm now at the stage where all the NPCs are now functional, at least at a basic level. This means no more spriting of NPCs required for the time being. I will likely need to add new objects to the world here and there to spruce it up, but these won't have to be animated "living" beings. Stationary objects aren't as much of a problem to work on for me. It's exciting to be moving on to filling up the world with creatures and objects. It's been a barren land for quite a while.