Phantom Quartus II Web version "13.1sp1" on Intel website
Intel has helpfully provided a page that shows the latest version of Quartus that supports a given device family. Unfortunately, some of the information there is incorrect.
See the information on the Cyclone II family: it says that Quartus II Web version "13.1sp1" supports the Cyclone II. As far as I can tell, 13.1sp1 does not and has not ever existed; the page links correctly to 13.0sp1, the last version of Quartus that supports the Cyclone II and other devices. 13.1 exists, but it doesn't support the Cyclone II.
The page "Quartus® Software Latest Version for Device Support" should be updated to replace all references to 13.1sp1 with 13.0sp1.
@_AK6DN_ pointed this out back in February but it wasn't fixed. I hope to bring attention to the issue so it can be fixed now.