First of all, thank you for trying the demo!
We've deployed a fix for the keyboard layout issue, WASD is now the default control scheme and you can switch to AZERTY at any time from the Options menu.
We also fixed an issue where the game would fail to launch due to an incorrect installation path. This has now been resolved. If you still see an error message from Steam, simply restart Steam and the game will launch normally.
We'll keep adding fixes and improvements as we work toward release, so we can give you the best experience possible. Thanks again for playing!