I put this in the generic "Game Programming" section, but I''m not getting any bites, I''ll try here. How are you guys resolving NPC positions? Right now in our code we have steering and formation code that attempt to move guys in a specific direction -- this is all well and good, until you need to resolve the y component of an NPC. In our last project we faked a solution by allowing a tolerance of +/- on the y axis for which a character could move, if you were above the tollerance, you would simply be unable to move, if you were bellow it, the NPC would start falling due to gravity. This has a bunch of issues (what if the tollerance is too low, or worse -- too high?). So, now we''ve picked up Novodex as a rigid body simulator, and I''m thinking of using it to resolve NPC positions. If anybody saw the presentation on Starcraft: Ghost at GDC, we''re trying to replicate that effect. The idea is we have an inverted cone, where the tip of the cone represents the NPC''s feet, and you apply a momentum to the cone based on where the NPC wants to move. The height of the cone will dictate the maximum vertical space you will be able to traverse, and things like gravity implicitly work themselves out in the physics simulation. The only catch is you need to do an extra step to set the desired position, then figure out where the physics actually tells you where the NPC is. Neither of these approaches is optimal, IMHO. On one hand you''ve got to write your own external force code (gravity, explosion forces, etc) and worry about threshold tollerances. On the other hand, you''ve got to deal with tweaking the physics system to get things just right (if the cone is on near flat ground, will gravity cause it to slide down the plane?). So, what do you guys do for your NPC code?