Thank you all for your comments!
I added a running speed with the middle mouse button. But the character animation is not yet done, I discovered blender and I'm not a fast guy..
There is indeed a problem with the movement. This probably comes from my fake 3d iso (I do not know much). I'll try to work around the problem by changing the speed of movement according to the axis.
My thinking was not so far I created this game especially to learn to use Constuct & Blender.
That said, the demo does not show much, I have some fun ideas
A new version is online: http://www.siine.eu/c2/