How to make a walking animation for a character in the BGE on a uneven or steep floor? I'm looking for a method to make a character walk properly to the angle of the floor.

So when he walks up a hill the feet have to be always touching the floor correctly and the walking motion of the legs has to change with the angle too. 

Walking the hill straight up or down is one thing, but imagining the character running sideways on it so that one leg is at a higher level than the other is more difficult.

Plus it will have a joystick-like rotation whilst walking so it blends from the "sidehill" animation to the uphill or downhill animation.

Does anyone have experience with this issue? Any tutorials, hints, tips, guesses, ressources, etc. would be much appreciated.

Any guesses on how to script this? E.g. how to change the model/animation according to the angle of the floor?
Ok,

you can change the angle of the step, easy enough with a ray, and parenting the animation
handles to a empty that animate the feet, just use track to another empty on the empty the feet animation handles are parented to, and place the empty via a ray. (so the player will walk up and down hills and change stride angle)

The hardest way (and best way) is this

http://www.youtube.com/watch?v=ZtzQAluEgts

This is a walking ragdoll, that uses the step offset angle code, along with the fact that it really walks.....

http://blenderartists.org/forum/showthread.php?353549-Non-PID-Ragdoll-based-on-Jackii-s-work-made-for-quot-Wrectified-quot

here is the 'base' of that rig.