Why does my mesh flatten on the X-axis in the game engine? I have a little lizard with a bone structure. Currently it has no animation and no game logic set. However, when pushing P, in game logic mode on the mesh, the mesh renders as a very squished version of itself, squished along the x-axis.

Also, none of the armature movements are visible, instead it's just what it was at default.



After pressing P, I get this:
Select your object and press CtrlA -> Apply Scale. This will set scale of both objects to 1.0, 1.0, 1.0.

Before you applied the scale, you must have scaled the objects along the X-Axis at one point. This will change the dimensions of the object, but the scale will be something like: 5.0, 1.0, 1.0. This won't change much in the 3D view, but BGE will reset all scales to 1.0 which (as you noticed) causes issues.