If you’re building a game, you’ll want your game agents and characters to exhibit realistic motion. A standard way of doing this is with ‘steering behaviors’.
The seminal paper by Craig Reynolds established a core set of steering behaviors that could be utilized for a variety of common movement tasks. These include such behaviors as predictive pursuit, fleeing, arrival, and wandering. This Ruby library can accomplish many/most of those tasks for your Ruby / JRuby game.
The basic behaviors can be layered for more complicated and advanced behaviors, such as flocking and crowd movement.
Embellishments and expansions are planned, but this is working software you can use to drive your own game’s characters. (I’m using it in my own game programming.) The Github repo includes working graphical examples, and you can install the Gem for easier and more direct use in your own game.
Pull requests are enthusiastically encouraged.