From: Physics- why not?

[treellama]

These simple components in LUA would work as long as the projectile is marked as guided (there might be more to adjust in the physics than that, but I can't think of any at the moment):

t = p:find_target()

and

if is_monster(t) then
proj.target = t

something like that...

Marking the projectile guided will not do anything against other players. Guided is only for monster -> player, or with the MML, player -> monster. Player -> player guided projectiles requires a real Lua script.