That is so awesome that you've played that LotR game. I have a box somewhere with a stack of floppies, and the Two Towers installment of that is in there, probably right next to Kid Pix.
Off the top of my head, I don't know of any VERGE games that exhibit that kind of behavior, but you could take a look at
this Sphere demo that I downloaded once upon a time. Specifically, scripts/battle.js. It
might help. Otherwise, I'd just try to make good use of the distance formula.