Ace Of Aces

As of version D0.10, Immortal Sins will no longer be compatible with Microsoft Windows Vista (including Service Pack 1 and Service Pack 2)for the Gamejolt and IndieDB versions. The installer will not install or update the game if the PC runs that OS version. In addtion, the installer will move over to Windows Installer 5.0 which is exclusive to Windows 7 and higher versions, to provide improved compatibility and new features

If you have subscribed to the Steam Workshop version, you can still play the game in Windows Vista.