Thanks for the comments chaps. This was a game at home. The terrain is a mix of buildings from the old Mordheim box set, some resin WW2-ish ruins, and the bridge was brought home, painted as you see it, from the aquarium section of the local pet store. Plus my lovely Zuzzy latex game mat.
For Swampy Jack we just sort of came up with logical-feeling rules as we went along. The basic idea was that if there were targets within his charge range he would attack, deciding which one to go after by a random die roll. Once he was in a fight he would stay there until his opponent was dead or had escaped, then he would choose a new target. I liked that better than always attacking the closest target, because it made him seem a bit more manic, sometimes running right past tough fighters to chew on weaker rear-echelon guys, or climbing up walls to attack non-obvious targets. During the melee phase we resolved combats between our forces as normal, but whenever Swampy Jack was fighting a character, we rolled off to see which one got to attack first.