Action maps are considered your average map. The maps that appear in the game are almost entirely Action maps. There is nothing that makes them stand out uniformly, but there is a lot of variety in them. Each map can have a different combination of enemies, or different tilesets, or different positioning of objects.
These are the most common kinds of maps on NUMA, and usually the most diverse.
Prisoner
A Prisoner map is a map where the ninja must stay between two (or more) zap drones while navigating through something resembling an obstacle course. They usually consist of long, narrow passages with many mines, and a few other obstacles. The most well-known map of this kind is 80-1: Prisoner by rrrobyp.