MudGrunt

I occasionally check the Free Wargames Rules site, and lo and behold,
someone has modified StarGrunt for medieval:
http://web.archive.org/web/20041015045724/http://mudgrunt.vildbasse.dk/

I've only lightly skimmed it so have no comments on its quality other
than
to say that some things are flat wrong--eg that pikes were useless
against
infantry, or that no one used untrained (yellow) troops--but you might
glean
some useful ideas.