Non blocking key input

@Echo off

 Del "%~n0_*.~K" 2> nul
 If not "%1"=="" Goto:%1

 Start "" /b "%~f0" Thread2
 break>"%~n0_Key.~K"
 Title 0 to stop
 Setlocal EnableDelayedExpansion
 For /l %%. in ()Do (
  (For /f "usebackq delims=" %%K in ("%~n0_Key.~K") Do Set "Key=%%K") 2> nul
  If "!Key!"=="0" (
   Endlocal
   EXIT
  )Else <nul set /p "=!Key!"
 )


:Thread2
 (For /l %%i in ()Do if not exist "%~n0_End.~K" (
   For /f "delims=" %%G  in ('Choice.exe /n /c:"0123456789abcdefghijklmnopqrstuvwxyz"')Do (
    >"%~n0_Key.~K" Echo(%%G
    If %%G==0 exit
   )
  )Else EXIT
 ) 2> nul
Goto:Thread2