You don't have to use anything special. Just code it. :V
Basically just have the main loop traverse through a bucket of objects (say, i.e., character objects) and invoke their "update" method. Within that update method you can have the characters do whatever like walking, or jumping or making basic choices or randomized movements etc.
Here's a dead project I made a while ago that you can take a look at. The zip includes a jar file that you can click to start the game without compiling the source first.http://heartpirates.com/archives/LD27_source.zip
It includes ad-hoc time management. Press number 1 to continue time, press 2 or 3 to stop time and while time is stopped you can press Q or E to go backwards/forwards in time. Mouse left click to spawn mobs that move by themselves.