Hmm how do you turn? It doesn't appear to register X/Y mouse movement at all.
I admittedly did not download the game from here after uploading it to trouble shoot. Lets see if something broke.
After downloading the game myself on here and doing some testing. The only thing I can think of is that you probably pushed ESC which uncaptures the mouse. Pressing Escape again will capture the mouse again so you can turn. As everything seemed fine to me when downloading it.