would it be possible to calibrate your arm length?
Generally yes and I will have to do that. Currently, there are only arms and they stretch a bit - this is mostly because you can't move your shoulders, ie. the game can't detect shoulder movement and I could estimate how they do move a little bit but it wouldn't be too reliable and stretching arms work anyway. What I mean by "stretching" is that not the mesh is stretched (as it is done in other games) but there are actuators inside arms that make them longer.
But this fails when a person is much taller or much shorter. And when the torso comes, it will be even more important.
The most probable solution at the moment is scaling the whole character depending on a mix of the height and arm's length. This way also hands will be scaled. There is a certain range of size that objects you take may have. I will have to check extremes to make sure you can pick up all objects - I don't want to limit player's actions depending on their height.
I just added adjusting door/room/corridor height and I am considering going a bit more crazy about it with the scale of the enemies. Although I don't know if that won't be too much.
I would love to have just a pure skeleton and to allow people to add armor and stuff on top of it. Or change some parameters to have a different look for various parts (hands!) or at least have some variations. I don't know how much possible it would be and it is not top priority. Enemy size could be fun too and I will be investigating that.
The actuators in the arms are only to make arms longer. There are also rails on which the arm moves. Arm without any armor plates looks weird but you see everything inside moving (stretching, twisting, rotating). ATM there are lots of things hardcoded but I always start with a hardcoded stuff for meshes and then I replace magic numbers with parameters.